Fluorinated monomer of cyclic acetal structure, polymer, resist protective coating composition, resist composition, and patterning process

ABSTRACT

A fluorinated monomer of cyclic acetal structure has formula (1) wherein R is a C 1 -C 20  alkyl group which may be substituted with halogen or separated by oxygen or carbonyl, and Z is a divalent organic group which forms a ring with alkylenoxy and contains a polymerizable unsaturated group. A polymer derived from the fluorinated monomer may be endowed with appropriate water repellency, water sliding property, lipophilicity, acid lability and hydrolyzability and is useful in formulating a protective coating composition and a resist composition.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application Nos. 2008-279212, 2008-279224 and 2008-279231filed in Japan on Oct. 30, 2008, Oct. 30, 2008 and Oct. 30, 2008,respectively, the entire contents of which are hereby incorporated byreference.

TECHNICAL FIELD

This invention relates to novel fluorinated monomers of cyclic acetalstructure capable of forming polymers which are fully transparent over awide spectrum ranging from visible light to wavelength 200 nm or shorterand fully water repellent, so that the monomers are useful as rawmaterials for the synthesis of opto-functional materials and coatingmaterials. Because of high transparency to ArF laser radiation and apossible choice of a proper structure so as to tailor propertiesincluding water repellency, lipophilicity, acid lability, andhydrolyzability, the polymers are useful as components for use in ArFlaser immersion lithography such as photoresist additives and protectivecoating materials.

This invention generally relates to a photolithography process for themicrofabrication of semiconductor devices, and particularly to animmersion photolithography process involving directing ArF excimer laserradiation of wavelength 193 nm from a projection lens toward aresist-coated substrate, with a liquid (e.g., water) intervening betweenthe lens and the substrate. More particularly, it relates to a resistprotective coating composition used to form a protective coating on aresist film for protection in the immersion photolithography, and aprocess for forming a pattern using the same. It also relates to aresist composition comprising the polymer, and a patterning processusing the resist composition.

BACKGROUND ART

In the recent drive for higher integration and operating speeds in LSIdevices, the pattern rule is made drastically finer. The backgroundsupporting such a rapid advance is a reduced wavelength of the lightsource for exposure. The change-over from i-line (365 nm) of a mercurylamp to shorter wavelength KrF laser (248 nm) enabled mass-scaleproduction of dynamic random access memories (DRAM) with an integrationdegree of 64 MB (processing feature size ≦0.25 μm). To establish themicropatterning technology necessary for the fabrication of DRAM with anintegration degree of 256 MB and 1 GB or more, the lithography using ArFexcimer laser (193 nm) is under active investigation. The ArF excimerlaser lithography, combined with a high NA lens (NA≦0.9), is consideredto comply with 65-nm node devices. For the fabrication of next 45-nmnode devices, the F₂ laser lithography of 157 nm wavelength became acandidate. However, because of many problems including a cost and ashortage of resist performance, the employment of F₂ lithography waspostponed. ArF immersion lithography was proposed as a substitute forthe F₂ lithography. Efforts have been made for the early introduction ofArF immersion lithography (see Proc. SPIE, Vol. 4690, xxix, 2002).

In the ArF immersion lithography, the space between the projection lensand the wafer is filled with water and ArF excimer laser is irradiatedthrough the water. Since water has a refractive index of 1.44 at 193 nm,pattern formation is possible even using a lens with NA of 1.0 orgreater. Theoretically, it is possible to increase the NA to 1.44. Theresolution is improved by an increment of NA. A combination of a lenshaving NA of at least 1.2 with ultra-high resolution technology suggestsa way to the 45-nm node (see Proc. SPIE, Vol. 5040, p 724, 2003).

Several problems arise when a resist film is exposed in the presence ofwater. For example, the acid once generated from a photoacid generatorand a basic compound added to the resist can be partially leached inwater. As a result, pattern profile changes and pattern collapse canoccur. It is also pointed out that water droplets remaining on theresist film, though in a minute volume, can penetrate into the resistfilm to generate defects.

These drawbacks of the ArF immersion lithography may be overcome byproviding a protective coating between the resist film and water toprevent resist components from being leached out and water frompenetrating into the resist film (see the 2nd Immersion Workshop, Resistand Cover Material Investigation for Immersion Lithography, 2003).

With respect to the protective coating on the photoresist film, atypical antireflective coating on resist (ARCOR) process is disclosed inJP-A 62-62520, JP-A 62-62521, and JP-A 60-38821. The ARCs are made offluorinated compounds having a low refractive index, such asperfluoroalkyl polyethers and perfluoroalkyl amines. Since thesefluorinated compounds are less compatible with organic substances,fluorocarbon solvents are used in coating and stripping of protectivecoatings, raising environmental and cost issues.

Other resist protective coating materials under investigation includewater-soluble or alkali-soluble materials. See, for example, JP-A6-273926, Japanese Patent No. 2803549, and J. Photopolymer Sci. andTechnol., Vol. 18, No. 5, p 615, 2005. Since the alkali-soluble resistprotective coating material is strippable with an alkaline developer, iteliminates a need for an extra stripping unit and offers a great costsaving. From this standpoint, great efforts have been devoted to developwater-insoluble resist protective coating materials, for example, resinshaving alkali-soluble groups such as fluorinated alcohol, carboxyl orsulfo groups on side chains. See WO 2005/42453, WO 2005/69676, JP-A2005-264131, JP-A 2006-133716, and JP-A 2006-91798.

Required of the resist protective coating materials are not only theability to prevent the generated acid and basic compound in thephotoresist film from being leached out in water and to prevent waterfrom penetrating into the resist film, but also such properties as waterrepellency and water sliding property. Of these properties, waterrepellency is improved by introducing fluorine into the resin and watersliding property is improved by combining water repellent groups ofdifferent species to form a micro-domain structure, as reported, forexample, in XXIV FATIPEC Congress Book, Vol. B, p 15 (1997) and Progressin Organic Coatings, 31, p 97 (1997).

One exemplary polymer exhibiting high water sliding property and waterrepellency is a fluorinated ring-closing polymerization polymer havinghexafluoroalcohol pendants. It is reported in Proc. SPIE, Vol. 6519, p651905 (2007) that this polymer is further improved in water slidingproperty by protecting hydroxyl groups on its side chains with acidlabile groups.

Although the introduction of fluorine into resins is effective not onlyfor improving water repellency, but also for improving water slidingproperties as demonstrated by sliding angle, receding contact angle orthe like, excessive introduction of fluorine results in resins with agreater surface contact angle following alkaline development. In thecurrent technology, those defects so called “blob defects” that occur onthe resist film surface (especially in the unexposed area) afterdevelopment are regarded problematic. A tendency is known that a resistfilm having higher water repellency suffers from more blob defects.Accordingly, introducing extra fluorine into resins for the purpose ofenhancing water repellency and water sliding property increases alikelihood of blob defects occurring.

It is believed that blob defects are caused by water droplets remainingon the resist film surface after development. The internal energy of awater droplet on a resist film increases in the spin drying step andreaches the maximum when the water droplet completely leaves the resistfilm surface. At the same time as the water droplet leaves the resistfilm surface, the resist film surface is damaged by that energy, whichis observable as blob defects.

The internal energy of a water droplet on a resist film is higher as thesurface becomes more water repellent. When a protective coating withhigher water repellency is disposed on a resist film, the resist surfacehas a greater contact angle due to intermixing between the resist filmand the protective coating, increasing a likelihood of blob defectsoccurring. This indicates that for the purpose of suppressing theoccurrence of blob defects, the surface contact angle after developmentmust be reduced to mitigate the internal energy of a water droplet.

Application of a more hydrophilic resist protective coating may beeffective for reducing the surface contact angle after development.However, such a protective coating provides a smaller receding contactangle, which interferes with high-speed scanning and allows waterdroplets to remain after scanning, giving rise to defects known as watermarks. A resist protective coating having carboxyl or sulfo groups isproposed in U.S. Pat. No. 7,455,952 (JP-A 2006-91798). Since bothcarboxyl and sulfo groups are fully hydrophilic, water repellency andwater sliding property worsen.

It is then proposed to form a protective coating from a blend of a firstpolymer having sulfo groups and a second polymer having highly waterrepellent hexafluoroalcohol groups such that the second polymer havinghexafluoroalcohol groups is segregated at the surface of the protectivecoating and the first polymer having sulfo groups is segregated at theinterface with the underlying resist. See 4th Immersion Symposium RE-04New Materials for surface energy control of 193 nm photoresists, DanSander et al. Although this protective coating is effective in reducingblob defects, the resist pattern suffers from film slimming afterdevelopment because sulfo groups bind with an amine component in theresist so that the amine component becomes depleted near the resistsurface. There exists a desire for a protective coating which preventsfilm slimming in order to produce a rectangular profile pattern andrenders more hydrophilic the resist surface after development in orderto inhibit blob defects.

The resist protective coating materials discussed above are needed notonly in the ArF immersion lithography, but also in the electron beam(EB) lithography. When EB lithography is performed for mask imagewriting, it is pointed out that the resist changes its sensitivity dueto evaporation of the acid generated during image writing, evaporationof vinyl ether produced by deprotection of acetal protective groups, orthe like, as discussed in JP-A 2002-99090. It is then proposed tosuppress resist sensitivity variation by applying a protective coatingmaterial to form a barrier film on top of a resist film.

As means for preventing resist components from being leached out andwater from penetrating into the resist film without a need for aprotective coating material, it is proposed in JP-A 2006-48029, JP-A2006-309245, and JP-A 2007-187887 to add an alkali-soluble, hydrophobic,high-molecular-weight compound as a surfactant to the resist material.This method achieves equivalent effects to the use of protective coatingmaterial because the hydrophobic compound is segregated at the resistsurface during resist film formation. Additionally, this method iseconomically advantageous over the use of a protective film becausesteps of forming and stripping the protective film are unnecessary.

It is believed that independent of whether the alkali-soluble surfactantor the resist protective coating material is used, water dropletsremaining on the resist film or protective film after scanning causefailure (or defects) in pattern formation. The ArF immersion lithographysystems commercially available at the present are designed such thatexposure is carried out by scanning the wafer-mounted stage at a speedof 300 to 550 mm/sec while water is partly held between the projectionlens and the wafer. In the event of such high-speed scanning, unless theperformance of the resist or protective film is sufficient, water cannotbe held between the projection lens and the wafer, and water dropletsare left on the surface of the resist film or protective film afterscanning. Such residual droplets can cause defects to the pattern.

To eliminate defects owing to residual droplets, it is necessary toimprove the flow or mobility of water (hereinafter, water slidingproperty) on the relevant coating film and the water repellency of thefilm. It is reported effective to increase the receding contact angle ofthe resist or protective film with water. See 2nd InternationalSymposium on Immersion Lithography, 12-15 Sep., 2005, Defectivity datataken with a full-field immersion exposure tool, Nakano et al.

For improving the water repellency of a coating film, introduction offluorine into a base resin is effective. For improving water slidingproperty, combining water-repellent groups of different species to forma microdomain structure is effective. See XXIV FATIPEC Congress Book,Vol. B, p 15 (1997) and Progress in Organic Coatings, 31, p 97 (1997).According to these reports, when a water molecule interacts with methyland trifluoromethyl groups, it orients via its oxygen and hydrogenatoms, and the orientation distance between water and methyl is longer.Thus a resin having not only water repellent fluorinated unitsintroduced, but also both fluoroalkyl and alkyl groups incorporated isimproved in water sliding property because of a longer orientationdistance of water.

One exemplary material known to have excellent water sliding propertyand water repellency is a copolymer of α-trifluoromethylacrylate andnorbornene derivative (Proc. SPIE, Vol. 4690, p 18, 2002). While thispolymer was originally developed as a highly transparent resin for F₂(157 nm) lithography resist materials, it is characterized by a regulararrangement of molecules of water repellent α-trifluoromethylacrylateand norbornene derivative in a ratio of 2:1. This characteristicarrangement increases the orientation distance of water relative to theresin and improves water sliding property. In fact, when this polymer isused as the base polymer in a protective coating for immersionlithography, water sliding property is drastically improved, asdescribed in JP-A 2007-140446 or US 20070122736.

Another example of the highly water repellent/water sliding performancematerial is a fluorinated ring-closing polymerization polymer havinghexafluoroalcohol groups on side chains. This polymer is furtherimproved in water sliding property by protecting hydroxyl groups on sidechains with acid labile groups, as reported in Proc. SPIE. Vol. 6519, p651905 (2007).

A material having good water sliding property performance is requirednot only from the standpoint of defects, but also from the standpoint ofproductivity. The immersion lithography needs higher throughputs thanever. For improved productivity, the exposure time must be reduced,which in turn requires high-speed scanning operation of the stage. Inorder to move the stage at a high speed while holding water beneath thelens, it is desired to have a resist material or resist protective filmhaving higher water sliding property performance.

The highly water repellent/water sliding performance materials discussedabove are expected to be applied not only to the ArF immersionlithography, but also to the resist material for mask blanks. Resistmaterials for mask blanks suffer from problems including a change ofsensitivity during long-term exposure in vacuum and long-term stabilityafter coating. With respect to the control of sensitivity changes invacuum, an improvement is made by a combination of acid labile groups ofacetal and tertiary ester types (U.S. Pat. No. 6,869,744). It isbelieved that after coating of a resist material, an amine component isadsorbed to the resist film surface whereby the resist varies itssensitivity or profile. A method of modifying the surface of a resistfilm for preventing adsorption of an amine component to the resist filmhas been devised.

CITATION LIST

-   -   Patent Document 1: JP-A S62-62520    -   Patent Document 2: JP-A S62-62521    -   Patent Document 3: JP-A S60-38821    -   Patent Document 4: JP-A H06-273926    -   Patent Document 5: JP 2803549    -   Patent Document 6: WO 2005/42453    -   Patent Document 7: WO 2005/69676    -   Patent Document 8: JP-A 2005-264131    -   Patent Document 9: JP-A 2006-133716    -   Patent Document 10: JP-A 2006-91798 (U.S. Pat. No. 7,455,952)    -   Patent Document 11: JP-A 2002-099090    -   Patent Document 12: JP-A 2006-048029    -   Patent Document 13: JP-A 2006-309245    -   Patent Document 14: JP-A 2007-187887    -   Patent Document 15: JP-A 2007-140446 (US 20070122736)    -   Patent Document 16: U.S. Pat. No. 6,869,744    -   Patent Document 17: JP-A 2008-111103 (U.S. Pat. No. 7,537,880,        KR 20080031643)    -   Patent Document 18: JP-A 2008-122932 (US 2008090172, KR        20080034789)    -   Non-Patent Document 1: Proc. SPIE, Vol. 4690, xxix, (2002)    -   Non-Patent Document 2: Proc. SPIE, Vol. 5040, p 724, (2003)    -   Non-Patent Document 3: 2nd Immersion Workshop: Resist and Cover        Material Investigation for Immersion Lithography (2003)    -   Non-Patent Document 4: J. Photopolymer Sci. and Technol., Vol.        18, No. 5, p 615, (2005)    -   Non-Patent Document 5: XXIV FATIPEC Congress Book, Vol. B, p 15        (1997)    -   Non-Patent Document 6: Progress in Organic Coatings, 31, p 97        (1997)    -   Non-Patent Document 7: Proc. SPIE, Vol. 6519, p 651905 (2007)    -   Non-Patent Document 8: 4th Immersion Symposium RE-04 New        Materials for surface energy control of 193 nm to photoresists,        Dan Sander et al.    -   Non-Patent Document 9: 2nd International Symposium on

Immersion Lithography, 12-15 September, (2005), Defectivity data takenwith a full-field immersion exposure tool, Nakano et al.

-   -   Non-Patent Document 10:Proc. SPIE, Vol. 4690, p 18, (2002)

SUMMARY OF INVENTION

An object of the present invention is to provide a novel fluorinatedmonomer and a polymer derived therefrom. The monomer is useful as a rawmaterial for the production of opto-functional materials and coatingmaterials and can be prepared from reactants which are readily availableand easy to handle; the polymer has high transparency to radiation ofwavelength 200 nm or shorter and improved water repellency, is designedsuch that any of its properties including water repellency,lipophilicity, acid lability and hydrolyzability may be tailored by achoice of a proper structure, and finds use as the materials adapted forArF laser exposure immersion lithography such as photoresist additivesand protective coating materials.

Another object is to provide a resist protective coating composition forimmersion lithography which has improved water repellency and watersliding property, causes few development defects, and allows forformation of a resist pattern of satisfactory profile after development;and a pattern forming process using the protective coating composition.

A further object is to provide a resist composition for immersionlithography which has improved water repellency and water slidingproperty, causes few development defects, and forms a resist pattern ofsatisfactory profile after development; and a pattern forming processusing the resist

The inventors have found that fluorinated monomers of cyclic acetalstructure having the general formulae (1), (2), (3), (4), (2-1), (3-1),(4-1), (2-2), (3-2), and (4-2) can be easily prepared from reactants,which are readily available and easy to handle, in high yields by themethod to be described later; and that polymers resulting frompolymerization of these fluorinated monomers have improved waterrepellency and allow their performance to be tailored by a choice ofstructure.

The inventors have also found that polymers of cyclic acetal structurehaving the general formulae (5) to (7) have sufficient water repellencyand water sliding property to serve as a base polymer in resistprotective coating materials and allow their performance to be tailoredby a choice of structure. When this polymer is blended with anotherpolymer containing a sulfonic acid amine salt within recurring units, aresist protective coating composition is obtained which enables to forma resist pattern of good profile with no or few development defects. Thepolymer has high transparency to radiation of wavelength 200 nm orshorter, is designed such that any of its properties including waterrepellency, lipophilicity, acid lability and hydrolyzability may betailored by a choice of a proper structure.

The inventors have further found that the polymers having the generalformulae (5) to (7) are useful as an additive polymer in resistmaterials.

The invention provides a fluorinated monomer, a polymer, a protectivecoating composition, a resist composition, and pattern forming processesusing the compositions, as defined below.

-   [1] A fluorinated monomer of cyclic acetal structure having the    general formula (1):

wherein R is a straight, branched or cyclic C₁-C₂₀ alkyl group in whichat least one hydrogen atom may be substituted by a halogen atom or atleast one methylene moiety may be substituted by an oxygen atom orcarbonyl group, and

Z is a divalent organic group which is attached at opposite ends to thealkylenoxy group to form a 5- or 6-membered ring and which contains apolymerizable unsaturated group.

-   [2] A fluorinated monomer of cyclic acetal structure having the    general formula (2), (3) or (4).

Herein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(2a), R^(2b),R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, with the proviso that said ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group,

R⁴ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup,

R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, at least one ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) is a monovalentorganic group containing a polymerizable unsaturated group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, with theproviso that said ring contains a polymerizable unsaturated group whenthe remaining groups of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) which do not participate in the ring formation do not contain apolymerizable unsaturated group,

R^(9a), R^(9b), R^(9a), and R^(9b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, at least one of R^(8a), R^(8b), R^(9a),and R^(9b) is a monovalent organic group containing a polymerizableunsaturated group, or any two of R^(8a), R^(8b), R^(9a), and R^(9b) maybond together to form a ring with the carbon atom to which they areattached, with the proviso that said ring contains a polymerizableunsaturated group when the remaining groups of R^(8a), R^(8b), R^(9a),and R^(9b) which do not participate in the ring formation do not containa polymerizable unsaturated group.

-   [3] A fluorinated monomer of cyclic acetal structure having the    general formula (2-1), (3-1) or (4-1).

Herein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(2a), R^(2b),R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, with the proviso that said ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group,

R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, at least one ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) is a monovalentorganic group containing a polymerizable unsaturated group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, with theproviso that said ring contains a polymerizable unsaturated group whenthe remaining groups of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) which do not participate in the ring formation do not contain apolymerizable unsaturated group,

R^(8a), R^(8b), R^(9a), and R^(9b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, at least one of R^(8a), R^(8b), R^(9a),and R^(9b) is a monovalent organic group containing a polymerizableunsaturated group, or any two of R^(8a), R^(8b), R^(9a), and R^(9b) maybond together to form a ring with the carbon atom to which they areattached, with the proviso that said ring contains a polymerizableunsaturated group when the remaining groups of R^(8a), R^(8b), R^(9a),and R^(9b) which do not participate in the ring formation do not containa polymerizable unsaturated group, and

R¹⁰ is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup.

-   [4] A fluorinated monomer of cyclic acetal structure having the    general formula (2-2), (3-2) or (4-2).

Herein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(2a), R^(2b),R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, with the proviso that said ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group,

R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are eachindepenedently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, at leastone of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) is amonovalent organic group containing a polymerizable unsaturated group,or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) maybond together to form a ring with the carbon atom to which they areattached, with the proviso that said ring contains a polymerizableunsaturated group when the remaining groups of R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), and R^(7b) which do not participate in the ringformation do not contain a polymerizable unsaturated group,

R^(8a), R^(8b), R^(9a), and R^(9b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, at least one of R^(8a), R^(8b), R^(9a),and R^(9b) is a monovalent organic group containing a polymerizableunsaturated group, or any two of R^(8a), R^(8b), R^(9a), and R^(9b) maybond together to form a ring with the carbon atom to which they areattached, with the proviso that said ring contains a polymerizableunsaturated group when the remaining groups of R^(8a), R^(8b), R^(9a),and R^(9b) which do not participate in the ring formation do not containa polymerizable unsaturated group,

R¹¹ is hydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group, and

R¹² is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup, or R¹¹ and R¹² may bond together to form a cyclic structure withthe carbon and oxygen atoms to which they are attached.

-   [5] The fluorinated monomer of cyclic acetal structure of any one of    [1] to [4] wherein the polymerizable unsaturated group is a group of    acrylate, methacrylate or α-trifluoromethylacrylate structure having    the general formula (A):

wherein R¹⁵ is hydrogen, methyl or trifluoromethyl, and the broken linedesignates a valence bond.

-   [6] The fluorinated monomer of cyclic acetal structure of any one of    [1] to [4] wherein the polymerizable unsaturated group is a group of    unsaturated hydrocarbon structure having the general formula (B) or    (C):

wherein p and q are each independently 1 or 0, and the broken linedesignates a valence bond.

-   [7] A polymer comprising recurring units of the general formula (5)    and having a weight average molecular weight of 1,000 to 500,000.

Herein R¹ is hydrogen, methyl or trifluoromethyl, and X is a structurehaving the general formula (X-1), (X-2) or (X-3),

in formula (X-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (X-1) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (X-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (X-2) is linked to the —(C═O)—O— linkage in recurring unit (5)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (X-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b),

R⁴ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup,

with the proviso that when the structure (X-1), (X-2) or (X-3) is linkedto the —(C═O)—O— linkage in recurring unit (5) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

-   [8] A polymer comprising recurring units of the general formula (6)    and having a weight average molecular weight of 1,000 to 500,000.

Herein R¹ is hydrogen, methyl or trifluoromethyl, and Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3),

in formula (Y-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Y-1) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (Y-2), R^(5a), R^(5b), R^(6a) , R^(6b), R^(7a), and R^(7b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (Y-2) is linked to the —(C═O)—O— linkage in recurring unit (6)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (Y-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Y-3) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), and

R¹⁰ is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup, with the proviso that when the structure (Y-1), (Y-2) or (Y-3) islinked to the —(C═O)—O— linkage in recurring unit (6) via a linkinggroup which is any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a),R^(5b), R^(6a), R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), andR^(9b), the linking group is an organic group as defined above, buthaving a valence bond as a result of one hydrogen atom being eliminatedtherefrom.

-   [9] A polymer comprising recurring units of the general formula (7)    and having a weight average molecular weight of 1,000 to 500,000.

Herein R¹ is hydrogen, methyl or trifluoromethyl, and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3),

in formula (Z-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Z-1) islinked to the—(C═O)—O— linkage in recurring unit (7) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (Z-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (Z-2) is linked to the —(C═O)—O— linkage in recurring unit (7)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Z-3) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b),

R¹¹ is hydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group,

R¹² is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup, or R¹¹ and R¹² may bond together to form a cyclic structure withthe carbon and oxygen atoms to which they are attached,

with the proviso that when the structure (Z-1), (Z-2) or (Z-3) is linkedto the —(C═O)—O— linkage in recurring unit (7) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

[10] The polymer of any one of [7] to [9], further comprising recurringunits of one or more type selected from the general formulae (8a) to(8f).

Herein R¹ is hydrogen, methyl or trifluoromethyl, R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached, R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group,R¹⁵ is a straight, branched or cyclic C₁-C₁₅ fluoroalkyl group, and R¹⁶is an acid labile group.

-   [11] A resist protective coating composition comprising a polymer    comprising recurring units of the general formula (5).

Herein R¹ is hydrogen, methyl or trifluoromethyl, and X is a structurehaving the general formula (X-1), (X-2) or (X-3),

in formula (X-1), R^(1a), R^(1b), R^(2a), and R^(2b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (X-1) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (X-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (X-2) is linked to the —(C═O)—O— linkage in recurring unit (5)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (X-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b),

R⁴ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup, with the proviso that when the structure (X-1), (X-2) or (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via a linkinggroup which is any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a),R^(5b), R^(6a), R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), andR^(9b), the linking group is an organic group as defined above, buthaving a valence bond as a result of one hydrogen atom being eliminatedtherefrom.

-   [12] A resist protective coating composition comprising a polymer    comprising recurring units of the general formula (6).

Herein R¹ is hydrogen, methyl or trifluoromethyl, and Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3),

in formula (Y-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Y-1) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (Y-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (Y-2) is linked to the —(C═O)—O— linkage in recurring unit (6)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (Y-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Y-3) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), and

R¹⁰ is i a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup,

with the proviso that when the structure (Y-1), (Y-2) or (Y-3) is linkedto the —(C═O)—O— linkage in recurring unit (6) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

-   [13] A resist protective coating composition comprising a polymer    comprising recurring units of the general formula (7)

Herein R¹ is hydrogen, methyl or trifluoromethyl, and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3),

in formula (Z-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Z-1) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (Z-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (Z-2) is linked to the —(C═O)—O— linkage in recurring unit (7)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Z-3) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b),

R¹¹ is hydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group,

R¹² is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup, or R¹¹ and R¹² may bond together to form a cyclic structure withthe carbon and oxygen atoms to which they are attached,

with the proviso that when the structure (Z-1), (Z-2) or (Z-3) is linkedto the —(C═O)—O— linkage in recurring unit (7) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

[14] The resist protective coating composition of any one of [11] to[13] wherein said polymer further comprises recurring units of one ormore type selected from the general formulae (8a) to (8f).

Herein R¹ is hydrogen, methyl or trifluoromethyl, R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached, R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group,R¹⁵ is a straight, branched or cyclic fluoroalkyl group, and R¹⁶ is anacid labile group.

-   [15] The protective coating composition of any one of [11] to [14],    further comprising a second polymer comprising recurring units of    the general formula (9) or (10).

Herein R^(31a) and R^(31b) are hydrogen or methyl,

R³² is a single bond, C₁-C₄ alkylene, phenylene, —C(═O)—O—, or—C(═O)—NH—,

R³³ is a single bond or a straight, branched or cyclic C₁-C₈ alkylenegroup,

R^(34a) to R^(34d) and R^(36a) to R^(36c) are each independentlyhydrogen, a straight, branched or cyclic C₁-C₁₂ alkyl, alkenyl, oxoalkylor oxoalkenyl group, C₆-C₂₀ aryl group, or C₇-C₁₂ aralkyl oraryloxoalkyl group, in which some or all hydrogen atoms may besubstituted by alkoxy groups, R^(34a) to R^(34d) and R^(36a) to R^(36c)may contain a nitrogen atom, ether group, ester group, hydroxyl group orcarboxyl group therein, any two of R^(34a) to R^(34d) and R^(36a) toR^(36c) may bond together to form a ring with the nitrogen atom to whichthey are attached, and when they form a ring, they are eachindependently a C₃-C₁₅ alkylene or a hetero-aromatic ring having thenitrogen atom therein,

R³⁵ is a straight, branched or cyclic C₁-C₈ alkylene group, and

R³⁷ is a straight, branched or cyclic C₁-C₂₀ alkyl group which maycontain carbonyl, ester, ether or halogen, or a C₆-C₁₅ aryl group whichmay contain carbonyl, ester, ether, halogen, or C₁-C₁₅ alkyl orfluoroalkyl.

-   [16] The protective coating composition of [15], wherein the second    polymer further comprises recurring units of the general formula    (11):

wherein R^(31c) is hydrogen or methyl, R^(38a) and R^(38b) are hydrogenor a straight, branched or cyclic C₁-C₁₅ alkyl group, or R^(38a) andR^(38b) may bond together to form a ring with the carbon atom to whichthey are attached.

-   [17] The protective coating composition of any one of [11] to [16],    further comprising a solvent.-   [18] The protective coating composition of [17] wherein the solvent    comprises an ether compound of 8 to 12 carbon atoms.-   [19] The protective coating composition of [17] or [18] wherein the    solvent comprises at least one ether compound of 8 to 12 carbon    atoms selected from the group consisting of di-n-butyl ether,    diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl    ether, di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether.-   [20] The protective coating composition of [18] or [19] wherein the    solvent comprises a mixture of the ether compound and 0.1 to 90% by    weight of an alcohol of 4 to 10 carbon atoms.-   [21] A pattern forming process comprising the steps of (1) applying    a resist material onto a substrate to form a photoresist film, (2)    applying the resist protective coating composition of any one of    [11] to [19] onto the photoresist film to form a protective coating    thereon, (3) heat treating and exposing the coated substrate to    high-energy radiation from a projection lens through a photomask    while holding a liquid between the substrate and the projection    lens, and (4) developing with a developer.-   [22] The process of [21] wherein the liquid is water.-   [23] The process of [21] or [22] wherein the high-energy radiation    has a wavelength in the range of 180 to 250 nm.-   [24] The process of any one of [21] to [23] wherein the developing    step uses a liquid alkaline developer for thereby developing the    photoresist film to form a resist pattern and stripping the resist    protective coating therefrom at the same time.-   [25] A lithography process for forming a pattern, comprising the    steps of forming a protective coating on a photoresist layer    disposed on a mask blank, exposing the layer structure in vacuum to    electron beam, and developing,

the protective coating being formed of the protective coatingcomposition of any one of [11] to [19].

-   [26] A resist composition comprising (A) a polymer comprising    recurring units of the general formula (5), (B) a base polymer    having a structure derived from lactone ring, hydroxyl group and/or    maleic anhydride, said base polymer becoming soluble in alkaline    developer under the action of acid, (C) a compound capable of    generating an acid upon exposure to high-energy radiation, and (D)    an organic solvent.

Herein R¹ is hydrogen, methyl or trifluoromethyl, and X is a structurehaving the general formula (X-1), (X-2) or (X-3),

in formula (X-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to forma ring withthe carbon atom to which they are attached, the structure (X-1) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (X-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (X-2) is linked to the —(C═O)—O— linkage in recurring unit (5)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (X-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b),

R⁴ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup,

with the proviso that when the structure (X-1), (X-2) or (X-3) is linkedto the —(C═O)—O— linkage in recurring unit (5) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

-   [27] A resist composition comprising (A) a polymer comprising    recurring units of the general formula (6), (B) a base polymer    having a structure derived from lactone ring, hydroxyl group and/or    maleic anhydride, said base polymer becoming soluble in alkaline    developer under the action of acid, (C) a compound capable of    generating an acid upon exposure to high-energy radiation, and (D)    an organic solvent.

Herein R¹ is hydrogen, methyl or trifluoromethyl, and Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3),

in formula (Y-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Y-1) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (Y-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (Y-2) is linked to the —(C═O)—O— linkage in recurring unit (6)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (Y-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Y-3) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), and

R¹⁰ is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup,

with the proviso that when the structure (Y-1), (Y-2) or (Y-3) is linkedto the —(C═O)—O— linkage in recurring unit (6) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

-   [28] A resist composition comprising (A) a polymer comprising    recurring units of the general formula (7), (B) a base polymer    having a structure derived from lactone ring, hydroxyl group and/or    maleic anhydride, said base polymer becoming soluble in alkaline    developer under the action of acid, (C) a compound capable of    generating an acid upon exposure to high-energy radiation, and (D)    an organic solvent.

Herein R¹ is hydrogen, methyl or trifluoromethyl, and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3),

in formula (Z-1), R^(2a), R^(2b), R^(3a), and R^(3b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Z-1) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(2a), R^(2b), R^(3a), and R^(3b),

in formula (Z-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, thestructure (Z-2) is linked to the —(C═O)—O— linkage in recurring unit (7)via any one of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b),

in formula (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, or any two ofR^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ring withthe carbon atom to which they are attached, the structure (Z-3) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b) ,

R¹¹ is hydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group,

R¹² is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup, or R¹¹ and R¹² may bond together to form a cyclic structure withthe carbon and oxygen atoms to which they are attached,

with the proviso that when the structure (Z-1), (Z-2) or (Z-3) is linkedto the —(C═O)—O— linkage in recurring unit (7) via a linking group whichis any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linkinggroup is an organic group as defined above, but having a valence bond asa result of one hydrogen atom being eliminated therefrom.

-   [29] A resist composition comprising (A) a polymer, (B) a base    polymer having a structure derived from lactone ring, hydroxyl group    and/or maleic anhydride, said base polymer becoming soluble in    alkaline developer under the action of acid, (C) a compound capable    of generating an acid upon exposure to high-energy radiation,    and (D) an organic solvent,

said polymer (A) comprises recurring units as set forth in [26], [27] or[28], and further recurring units of one or more type selected from thegeneral formulae (8a) to (8f):

wherein R¹ is hydrogen, methyl or trifluoromethyl, R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached, R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group,R¹⁵ is a straight, branched or cyclic C₁-C₁₅ fluoroalkyl group, and R¹⁶is an acid labile group.

-   [30] The resist composition of any one of [26] to [29], further    comprising (E) a basic compound.-   [31] The resist composition of any one of [26] to [30], further    comprising (F) a dissolution regulator.-   [32] A pattern forming process comprising the steps of (1) applying    the resist composition of any one of [26] to [31] onto a substrate    to form a resist film, (2) heat treating the resist film and    exposing it to high-energy radiation through a photomask, and (3)    developing the exposed resist film with a developer.-   [33] A pattern forming process comprising the steps of (1) applying    the resist composition of any one of [26] to [31] onto a substrate    to form a resist film, (2) heat treating the coated substrate, and    exposing it to high-energy radiation through a photomask while    keeping a liquid between a projection lens and the coated substrate,    and (3) developing the exposed resist film with a developer.-   [34] A pattern forming process comprising the steps of (1) applying    the resist composition of any one of [26] to [31] onto a substrate    to form a resist film, (2) forming a protective coating on the    resist film, (3) heat treating the coated substrate, and exposing it    to high-energy radiation through a photomask while keeping a liquid    between a projection lens and the coated substrate, and (4)    developing the exposed resist film with a developer.-   [35] The process of [33] or [34], wherein the liquid is water.-   [36] The process of any one of [32] to [35], wherein an exposure    light source emits high-energy radiation having a wavelength of 180    to 250 nm.-   [37] A pattern forming process comprising the steps of (1) applying    the resist composition of any one of [26] to [31] onto a mask blank    substrate to form a coating, (2) heat treating the coating and    irradiating it in vacuum with an electron beam, and (3) developing    the coating with a developer.

ADVANTAGEOUS EFFECTS OF INVENTION

The fluorinated monomer of cyclic acetal structure is useful as a rawmaterial for the production of opto-functional materials and coatingmaterials and can be prepared from reactants which are readily availableand easy to handle. The polymer derived therefrom has high transparencyto radiation of wavelength 200 nm or shorter and improved waterrepellency, is designed such that any of its properties including waterrepellency, lipophilicity, acid lability and hydrolyzability may betailored by a choice of a proper structure, and finds use as thematerials adapted for ArF laser exposure immersion lithography such asphotoresist additives and protective coating materials.

The resist protective coating composition comprising the polymer ofcyclic acetal structure forms a film which has a high receding contactangle sufficient to prevent leach-out of resist components andpenetration of water, and allows for formation of a resist pattern ofsatisfactory profile without defects after development when processed byimmersion lithography.

The resist composition comprising the polymer as an additive allows forformation of a resist pattern of satisfactory profile after developmentwhen processed by immersion lithography.

DESCRIPTION OF EMBODIMENTS

The singular forms “a”, “an” and “the” include plural referents unlessthe context clearly dictates otherwise.The notation (Cn-Cm) means agroup containing from n to m carbon atoms per group.

The abbreviation Me is methyl, and Ac is acetyl.

Fluorinated Monomer

One embodiment of the invention is a fluorinated monomer of cyclicacetal structure represented by the general formula (1):

wherein R is a straight, branched or cyclic C₁-C₂₀ alkyl group in whichat least one hydrogen atom may be substituted by a halogen atom or atleast one methylene moiety may be substituted by an oxygen atom orcarbonyl group, and Z is a divalent organic group which is attached atopposite ends to the alkylenoxy group to form a 5- or 6-membered ringand which contains a polymerizable unsaturated group.

In general, the acetal is known labile to acid. It is thus believed thatthe cyclic acetal structure in the fluorinated monomer is decomposableunder the action of an acid generated by an acid generator, for example.In this case, the cyclic acetal is decomposed to form a hydrophilichemiacetal structure, whereby the contact angle of polymer surface isreduced.

It is preferred for ease of preparation that the fluorinated monomerhave a structure represented by the general formula (2), (3) or (4).

Herein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, and at least one of R^(2a),R^(2b), R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group. Any two of R^(2a), R^(2b), R^(3a), andR^(3b) may bond together to form a ring with the carbon atom to whichthey are attached, with the proviso that the ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group. R⁴ is astraight, branched or cyclic C₁-C₂₀ alkyl group in which at least onehydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group.R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, and at least one ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) is a monovalentorganic group containing a polymerizable unsaturated group. Any two ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond together toform a ring with the carbon atom to which they are attached, with theproviso that the ring contains a polymerizable unsaturated group whenthe remaining groups of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) which do not participate in the ring formation do not contain apolymerizable unsaturated group. R^(8a), R^(8b), R^(9a), and R^(9b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, and atleast one of R^(8a), R^(8b), R^(9a), and R^(9b) is a monovalent organicgroup containing a polymerizable unsaturated group. Any two of R^(8a),R^(8b), R^(9a), and R^(9b) may bond together to form a ring with thecarbon atom to which they are attached, with the proviso that the ringcontains a polymerizable unsaturated group when the remaining groups ofR^(8a), R^(8b), R^(9a), and R^(9b) which do not participate in the ringformation do not contain a polymerizable unsaturated group.

In the foregoing formulae, the structure of the groups represented by Z,R, R^(2a), R^(2b), R^(3a), R^(3b), R⁴, R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b) and the substitutionposition of a polymerizable unsaturated group thereon may be determinedas appropriate depending on various conditions such as ease ofpreparation and polymerization ability of the monomer, and physicalproperties of a polymer synthesized therefrom.

Z is a divalent organic group containing a polymerizable unsaturatedgroup. Typical are straight, branched or cyclic divalent C₁-C₁₅ organicgroups containing a polymerizable unsaturated group. Suitable divalentorganic groups are obtained from monovalent hydrocarbon groups bysubstituting a single bond for one hydrogen atom, and furthersubstituting a polymerizable unsaturated group for another hydrogenatom, while suitable monovalent hydrocarbon groups include straight,branched or cyclic alkyl groups such as methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, n-nonyl, n-decyl, cyclopropyl, cyclobutyl,cyclopentyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl,cyclohexyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl,methylcyclohexylmethyl, ethylcyclohexylmethyl, ethylcyclohexylethyl,bicyclo[2.2.1]heptyl, bicyclo[2.2.1]heptylmethyl,bicyclo[2.2.1]heptylethyl, bicyclo[2.2.1]heptylbutyl,methylbicyclo[2.2.1]heptylmethyl, ethylbicyclo[2.2.1]heptylmethyl,ethylbicyclo[2.2.1]heptylethyl, bicyclo[2.2.2]octyl,bicyclo[2.2.2]octylmethyl, bicyclo[2.2.2]octylethyl,bicyclo[2.2.2]octylbutyl, methylbicyclo[2.2.2]octylmethyl,ethylbicyclo[2.2.2]octylmethyl, ethylbicyclo[2.2.2]octylethyl,tricyclo[5.2.1.0^(2,6)]decyl, tricyclo[5.2.1.0^(2,6)]decylmethyl,tricyclo[5.2.1.0^(2,6)]decylethyl, tricyclo[5.2.1.0^(2,6)]decylbutyl,methyltricyclo[5.2.1.0^(2,6)]decylmethyl,ethyltricyclo[5.2.1.0^(2,6)]decylmethyl,ethyltricyclo[5.2.1.0^(2,6)]decylethyl, adamantyl, adamantylmethyl,adamantylethyl, adamantylbutyl, methyladamantylmethyl,ethyladamantylmethyl, ethyladamantylethyl,tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecyl,tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecylmethyl,tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecylethyl,tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecylbutyl,tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecylmethyl,ethyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecylmethyl, andethyltetracyclo[4.4.0.1^(2.5).1^(7,10)]dodecylethyl; aryl groups such asphenyl, tolyl, naphthyl, anthryl, and phenanthryl; and aralkyl groupssuch as benzyl, diphenylmethyl, and phenethyl. In the foregoing groups,one or more hydrogen atoms may be substituted by halogen, alkyl, aryl,alkoxy, alkoxycarbonyl or oxo groups.

R and R⁴ each are a straight, branched or cyclic C₁-C₂₀ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group. While those groups of the formula —CO—R¹⁰ or—CH(R¹¹)—OR¹² to be described later are desired, other suitable alkylgroups include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, tert-amyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl,n-decyl, eicosanyl, cyclopropyl, cyclobutyl, cyclopentyl,cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexyl,cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl,methylcyclohexylmethyl, ethylcyclohexylmethyl, ethylcyclohexylethyl,bicyclo[2.2.1]heptyl, trifluoromethyl, 2,2,2-trifluoroethyl,2,2,3,3,3-pentafluoropropyl, 2-methoxyethyl,2-(hexafluoroisopropoxy)ethyl, 2-acetoxyethyl, and acetonyl. Byselecting an optimum structure as R or R⁴, properties such as waterrepellency and lipophilicity may be tailored as required.

R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group. At least one of R^(2a), R^(2b), R^(3a),and R^(3b) is a monovalent organic group containing a polymerizableunsaturated group. The straight, branched or cyclic monovalent C₁-C₁₅organic group include monovalent hydrocarbon groups, for example,straight, branched or cyclic alkyl groups such as methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, n-nonyl, n-decyl, cyclopropyl, cyclobutyl,cyclopentyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl,cyclohexyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl,methylcyclohexylmethyl, ethylcyclohexylmethyl, ethylcyclohexylethyl,bicyclo[2.2.1]heptyl, bicyclo[2.2.1]heptylmethyl,bicyclo[2.2.1]heptylethyl, bicyclo[2.2.1]heptylbutyl,methylbicyclo[2.2.1]heptylmethyl, ethylbicyclo[2.2.1]heptylmethyl,ethylbicyclo[2.2.1]heptylethyl, bicyclo[2.2.2]octyl,bicyclo[2.2.2]octylmethyl, bicyclo[2.2.2]octylethyl,bicyclo[2.2.2]octylbutyl, methylbicyclo[2.2.2]octylmethyl,ethylbicyclo[2.2.2]octylmethyl, ethylbicyclo[2.2.2]octylethyl,tricyclo[5.2.1.0^(2,6)]decyl, tricyclo[5.2.1.0^(2,6)]decylmethyl,tricyclo[5.2.1.0^(2,6)]decylethyl, tricyclo[5.2.1.0^(2,6)]decylbutyl,methyltricyclo[5.2.1.0^(2,6)]decylmethyl,ethyltricyclo[5.2.1.0^(2,6)]decylmethyl,ethyltricyclo[5.2.1.0^(2,6)]decylethyl, adamantyl, adamantylmethyl,adamantylethyl, adamantylbutyl, methyladamantylmethyl,ethyladamantylmethyl, ethyladamantylethyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylmethyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylethyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylbutyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylmethyl,ethyltetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylmethyl, andethyltetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylethyl, aryl groups such asphenyl, methylphenyl, naphthyl, anthryl, and phenanthryl, and aralkylgroups such as benzyl, diphenylmethyl and phenethyl; alkoxy groups suchas methoxy, ethoxy and propoxy, and acyloxy groups such as formyloxy andacetoxy. In the foregoing groups, one or more hydrogen atoms may besubstituted by halogen, alkyl, aryl, alkoxy, alkoxycarbonyl, oxo,alkoxyalkyl, acyloxy, acyloxyalkyl, alkoxyalkoxy or other groups. Interalia, hydrogen, hydroxyl, halogen, methyl, ethyl, propyl, tert-butyl,and perfluoroalkyl groups are preferred. The monovalent organic groupcontaining a polymerizable unsaturated group may be a polymerizableunsaturated group itself or a monovalent organic group as listed abovein which one hydrogen atom is substituted by a polymerizable unsaturatedgroup.

A combination of any two of R^(2a), R^(2b), R^(3a), and R^(3b) may bondtogether to form a ring with the carbon atom to which they are attached.Typical ring-forming pairs include a pair of R^(2a) and R^(2b), R^(2a)and R^(3a), R^(2a) and R^(3b), R^(2b) and R^(3a), R^(2b) and R^(3b), andR^(3a) and R^(3b). Exemplary rings thus formed include C₃-C₁₂ alicyclichydrocarbons such as cyclopropane, cyclobutane, cyclopentane,cyclohexane, bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane,tricyclo[5.2.1.0^(2,6)]decane, adamantane, andtetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecane as well as fused ringscontaining any of the foregoing. In the foregoing alicyclichydrocarbons, one or more hydrogen atoms may be substituted by hydroxyl,halogen, alkyl, aryl, alkoxy, alkoxycarbonyl, oxo, alkoxyalkyl, acyloxy,acyloxyalkyl, alkoxyalkoxy or other groups.

It is noted that the ring contains a polymerizable unsaturated groupwhen the remaining groups of R^(2a), R^(2b), R^(3a), and R^(3b) which donot participate in the ring formation (for example, R^(3a) and R^(3b)when R^(2a) and R^(2b) form a ring, or R^(2b) and R^(3b) when R^(2a) andR^(3a) form a ring) do not contain a polymerizable unsaturated group.

R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are as exemplifiedfor R^(2a), R^(2b), R^(3a), and R^(3b). Typical ring-forming pairsinclude a pair of R^(5a) and R^(5b), R^(5a) and R^(6a), R^(5a) andR^(6b), R^(5b) and R^(6a), R^(5b) and R^(6b), R^(6a) and R^(6b), R^(6a)and R^(7a), R^(6a) and R^(7b), R^(6b) and R^(7a), R^(6a) and R^(7b), andR^(7a) and R^(7b). The same applies to R^(8a), R^(8b), R^(9a), andR^(9b), and typical ring-forming pairs include a pair of R^(8a) andR^(8b), and R^(9a) and R^(9b).

The fluorinated monomer of the invention may be endowed with alkalinehydrolyzability depending on the desired performance. In such a case,the fluorinated monomer preferably has a structure of the generalformula (2-1), (3-1) or (4-1). Hemiacetal hydroxyl group has a higheracidity than alcoholic hydroxyl group. Since the ester bond in formula(2-1), (3-1) or (4-1) is an ester between a carboxylic acid and ahemiacetal hydroxyl group having a further higher acidity as a result offive fluorine atoms bonding to vicinal carbon atoms, and thus regardedas mixed acid anhydride, this ester is highly susceptible to alkalinehydrolysis as compared with esters of carboxylic acid with ordinaryalcohol. It is thus believed that this ester is readily hydrolyzed withan alkaline developer, for example. When the ester bond in formula(2-1), (3-1) or (4-1) is hydrolyzed, a highly hydrophilic hemiacetalstructure forms whereby the contact angle at polymer surface is reduced.

Herein R″ through R^(9b) are as defined and exemplified above, and R¹⁰is a straight, branched or cyclic C₁-C₁₉ alkyl group in which at leastone hydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group.

R¹⁰ is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup. Suitable alkyl groups include methyl, ethyl, propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, isobutyl, tert-amyl, n-pentyl,neopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, nonadecyl,cyclopropyl, cyclobutyl, cyclopentyl, cyclopentylmethyl,cyclopentylethyl, cyclopentylbutyl, cyclohexyl, cyclohexylmethyl,cyclohexylethyl, cyclohexylbutyl, methylcyclohexylmethyl,ethylcyclohexylmethyl, ethylcyclohexylethyl, bicyclo[2.2.1]heptyl,trifluoromethyl, 2,2,2-trifluoroethyl, 2,2,3,3,3-pentafluoropropyl,1-methyl-2,2,2-trifluoroethyl, 2-methoxyethyl,2-(hexafluoroisopropoxy)ethyl, 2-acetoxyethyl, and acetonyl. Byselecting an optimum structure as R¹⁰, properties such as alkalinehydrolysis, water repellency and lipophilicity may be tailored asrequired.

Also the fluorinated monomer of the invention may be endowed with higheracid lability depending on the desired performance. In such a case, thefluorinated monomer preferably has a structure of the general formula(2-2), (3-2) or (4-2). It is believed that the acid labile acetalstructure (—O—CH(R¹¹)—OR¹²) included in formula (2-2), (3-2) or (4-2)will be readily decomposed if an acid generated by an acid generator ispresent in proximity thereto. When the acetal structure(—O—CH(R¹¹)—OR¹²) in formula (2-2), (3-2) or (4-2) is decomposed, ahighly hydrophilic hemiacetal structure forms whereby the contact angleat polymer surface is reduced.

Herein R^(2a) through R^(9b) are as defined and exemplified above, R¹¹is hydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group. R¹² is a straight, branched or cyclic C₁-C₁₉ alkyl groupin which at least one hydrogen atom may be substituted by a halogen atomor at least one methylene moiety may be substituted by an oxygen atom orcarbonyl group. R¹¹ and R¹² may bond together to form a cyclic structurewith the carbon and oxygen atoms to which they are attached.

R¹¹ is hydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group inwhich at least one hydrogen atom may be substituted by a halogen atom orat least one methylene moiety may be substituted by an oxygen atom orcarbonyl group. Suitable groups of R¹¹ include hydrogen, methyl, ethyl,propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, tert-amyl,n-pentyl, 2-pentyl, 3-pentyl, neopentyl, n-hexyl, 2-hexyl, 3-hexyl,n-heptyl, n-octyl, n-nonyl, n-decyl, octadecyl, cyclopropyl, cyclobutyl,cyclopentyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl,cyclohexyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl,methylcyclohexylmethyl, ethylcyclohexylmethyl, ethylcyclohexylethyl,bicyclo[2.2.1]heptyl, trifluoromethyl, 2,2,2-trifluoroethyl,2,2,3,3,3-pentafluoropropyl, 1-methyl-2,2,2-trifluoroethyl,2-methoxyethyl, 2-(hexafluoroisopropoxy)ethyl, 2-acetoxyethyl, andacetonyl.

R¹² is a straight, branched or cyclic C₁-C₁₉ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup. Suitable alkyl groups include methyl, ethyl, propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, n-nonyl, n-decyl, cyclopropyl, cyclobutyl, cyclopentyl,cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexyl,cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl,methylcyclohexylmethyl, ethylcyclohexylmethyl, ethylcyclohexylethyl,bicyclo[2.2.1]heptyl, bicyclo[2.2.1]heptylmethyl,bicyclo[2.2.1]heptylethyl, bicyclo[2.2.1]heptylbutyl,methylbicyclo[2.2.1]heptylmethyl, ethylbicyclo[2.2.1]heptylmethyl,ethylbicyclo[2.2.1]heptylethyl, bicyclo[2.2.2]octyl,bicyclo[2.2.2]octylmethyl, bicyclo[2.2.2]octylethyl,bicyclo[2.2.2]octylbutyl, methylbicyclo[2.2.2]octylmethyl,ethylbicyclo[2.2.2]octylmethyl, ethylbicyclo[2.2.2]octylethyl,tricyclo[5.2.1.0^(2,6)]decyl, tricyclo[5.2.1.0^(2,6)]decylmethyl,tricyclo[5.2.1.0^(2,6)]decylethyl, tricyclo[5.2.1.0^(2,6)]decylbutyl,methyltricyclo[5.2.1.0^(2,6)]decylmethyl,ethyltricyclo[5.2.1.0^(2,6)]decylmethyl,ethyltricyclo[5.2.1.0^(2,6)]decylethyl, adamantyl, adamantylmethyl,adamantylethyl, adamantylbutyl, methyladamantylmethyl,ethyladamantylmethyl, ethyladamantylethyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylmethyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylethyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylbutyl,tetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylmethyl,ethyltetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylmethyl,ethyltetracyclo[4.4.0.1^(2,5)1^(7,10)]dodecylethyl, trifluoromethyl,2,2,2-trifluoroethyl, 2,2,3,3,3-pentafluoropropyl,1-methyl-2,2,2-trifluoroethyl, 2-methoxyethyl,2-(hexafluoroisopropoxy)ethyl, 2-acetoxyethyl,2-(1-adamantylcarbonyloxy)ethyl, and acetonyl.

R¹¹ and R¹² may bond together to form a cyclic structure with the carbonand oxygen atoms to which they are attached. Examples of the cyclicstructure formed by R¹¹ and R¹² include tetrahydrofuran,methyltetrahydrofuran, methoxytetrahydrofuran, tetrahydropyran,methyltetrahydropyran, methoxytetrahydropyran, 1,4-dioxane rings. Byselecting an optimum structure as R¹¹ and R¹², properties such as acidlability, water repellency and lipophilicity may be tailored asrequired.

The polymerizable unsaturated group included in formulae (1), (2), (3),(4), (2-1), (3-1), (4-1), (2-2), (3-2), and (4-2) may be any doublebond-bearing group capable of polymerization by polymerization meanssuch as radical polymerization, anionic polymerization or cationicpolymerization. Suitable polymerizable unsaturated group-bearingstructures include unsaturated hydrocarbon structures such asbicyclo[2.2.1]hept-2-ene, tricyclo[5.2.1.0^(2,6)]dec-8-ene,tetracyclo[4.4.0.1^(2,5).1″]dodec-3-ene, unsaturated ether structuressuch as vinyloxy and allyloxy, α,β-unsaturated ketone structures such asvinylketone and isopropenylketone, α,β-unsaturated ester structures suchas acrylate, methacrylate, α-trifluoromethylacrylate andα-fluoroacrylate, and unsaturated hydrocarbon ester structures such asbicyclo[2.2.1]hept-5-ene-5-carboxylate andtetracyclo[4.4.0.1^(2,5.)1^(7,10)]dodec-8-ene-3-carboxylate. Of these,those groups of α,β-unsaturated ester structure having the generalformula (A) below are preferred. Namely, acrylate, methacrylate andα-trifluoromethylacrylate structures are preferred.

Herein R¹⁵ is hydrogen, methyl or trifluoromethyl, and the broken linedesignates a valence bond.

The polymerizable unsaturated group may also be a group of unsaturatedhydrocarbon structure having the general formula (B) or (C).

Herein p and q are each independently 1 or 0, and the broken linedesignates a valence bond.

It is preferred that the divalent organic group represented by Z or thepolymerizable unsaturated group-containing monovalent organic group orpolymerizable unsaturated group-containing ring represented by R^(2a) toR^(9b) contain a polymerizable unsaturated group of the above formula(A), (B) or (C). In this case, the polymerizable unsaturated group offormula (A) or (C) is incorporated in Z or polymerizable unsaturatedgroup-containing ring in the form wherein its single valance bond bindswith any one valence bond of a trivalent linking group. The trivalentlinking group is preferably a straight, branched or cyclic C₁-C₁₀alkylene group which may have substituted thereon a hydroxyl, halogen,alkoxy, alkoxyalkyl, alkoxyalkoxy, acyloxy, acyloxyalkyl or othergroups, with one hydrogen atom being replaced by a single bond (orvalence bond). The polymerizable unsaturated group of formula (A) or (C)is incorporated in the polymerizable unsaturated group-containingmonovalent organic group represented by R^(2a) to R^(9b) in twodifferent forms. In one form, the group of formula (A) or (C) as suchconstitutes the polymerizable unsaturated group-containing monovalentorganic group, and this group binds directly with a carbon atom(designated carbon atom “C”), that is, the valence bond of formula (A)or (C) binds directly with carbon atom “C”. In the other form, the groupof formula (A) or (C) binds with carbon atom “C” via a divalent linkinggroup, preferably a straight, branched or cyclic C₁-C₁₀ alkylene group,that is, the valence bond of formula (A) or (C) binds with carbon atom“C” via a divalent linking group.

As to the polymerizable unsaturated group of formula (B), preferably oneor two of its valence bonds become the valence bond via which said groupis incorporated in Z or the polymerizable unsaturated group-containingmonovalent organic group or polymerizable unsaturated group-containingring represented by R^(2a) to R^(9b), while the remaining valence bondspreferably bind with hydrogen atoms, hydroxyl groups, halogen atoms, orstraight, branched or cyclic C₁-C₁₅ organic groups (as exemplifiedabove).

The form wherein one valence bond of formula (B) is incorporated in Z orthe polymerizable unsaturated group-containing monovalent organic groupor polymerizable unsaturated group-containing ring represented by R^(2a)to R^(9b) is the same as that of the valance bond of formula (A) or (C).The form wherein two valence bonds of formula (B) are incorporated in Zor the polymerizable unsaturated group-containing ring includes the formwherein the group of formula (B) itself constitutes Z or the relevantring, and the form wherein one or both of the two valence bonds bindwith the divalent linking group to constitute Z or the relevant ring.The form wherein two valence bonds of formula (B) are incorporated inthe polymerizable unsaturated group-containing monovalent organic groupincludes the form wherein two valence bonds bind with the divalentlinking groups which bind with a carbon atom at an appropriate positionto form a ring, which constitutes the polymerizable unsaturatedgroup-containing monovalent organic group.

Notably, the form wherein two valence bonds of formula (B) bind with thestructure of formula (2) is exemplified by a spiro ring represented bythe formula:

wherein p is as defined above, or a fused ring represented by theformula:

wherein p is as defined above.

Examples of the linking group are given below.

In the fluorinated monomers of cyclic acetal structure represented byformulae (1), (2), (3), (4), (2-1), (3-1), (4-1), (2-2), (3-2), and(4-2), some carbon atoms constituting the molecule may become asymmetricdepending on the type and combination of groups represented by Z, R, R⁴,R^(2a) to R^(9b), and R¹⁰ to R¹², indicating that there can existenantiomers and diastereomers. Each of formulae (1), (2), (3), (4),(2-1), (3-1), (4-1), (2-2), (3-2), and (4-2) collectively represents allsuch stereoisomers. Such stereoisomers may be used alone or inadmixture.

Examples of the fluorinated monomers of cyclic acetal structurerepresented by formulae (1), (2), (3), (4), (2-1), (3-1), (4-1), (2-2),(3-2), and (4-2) are given below, but not limited thereto.

Below described is how to prepare the fluorinated monomers of theinvention. The fluorinated monomers of cyclic acetal structurerepresented by formulae (1), (2), (3), (4), (2-1), (3-1), (4-1), (2-2),(3-2), and (4-2) are preferably prepared by an appropriate methodselected in accordance with a particular structure of monomer. Oneexemplary method is O-alkylation or O-acylation of a correspondinghemiacetal compound although the invention is not limited thereto. Thesynthesis of an acetal compound (1) from a hemiacetal compound (1′)according to the following scheme is described in detail as a typicalexample.

Herein Z and R are as defined above, and X is a leaving group.

The hemiacetal compound (1′) used as the starting reactant may becommercially prepared by a method known from JP-A 2006-152255. In theformula, X is a leaving group, examples of which include halogen atomssuch as chlorine, bromine and iodine, alkanesulfonyloxy groups such asmethanesulfonyloxy, arenesulfonyloxy groups such asp-toluenesulfonyloxy, acyloxy groups such as acetoxy, aryloxy groupssuch as pentafluorophenoxy, and nitrogen-containing leaving groups suchas imidazoyl. When R is alkyl, RX is an alkylating agent and thereaction is O-alkylation. When R is acyl, RX is an acylating agent andthe reaction is O-acylation. An amount of RX used is desirably 0.3 to 10moles, and more desirably 0.8 to 5 moles per mole of hemiacetal compound(1′).

The reaction may be carried out in a solventless system or in a solvent.Suitable solvents include alcohols such as methanol, ethanol, isopropylalcohol, t-butyl alcohol and ethylene glycol; hydrocarbons such ashexane, heptane, benzene, toluene and xylene; ethers such as diethylether, dibutyl ether, tetrahydrofuran, 1,4-dioxane, and diglyme;chlorinated solvents such as methylene chloride, chloroform, and1,2-dichloroethylene; aprotic polar solvents such asN,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, andN-methylpyrrolidone; carboxylic acids such as formic acid and aceticacid; esters such as ethyl acetate and butyl acetate; ketones such asacetone and 2-butanone; nitriles such as acetonitrile; amines such aspyridine and triethylamine; and water. Depending on reaction conditions,any of the foregoing solvents may be selected and used alone or inadmixture.

The reaction temperature may be selected in the range of −40° C. to thereflux temperature of the solvent, depending on the desired reactionrate. To the reaction system, a base or transition metal salt ispreferably added in order to increase the conversion. Suitable basesinclude amines such as pyridine, triethylamine, diisopropylethylamine,4-dimethylaminopyridine, and imidazole; metal alkoxides such as sodiummethoxide, sodium ethoxide, and potassium t-butoxide; carbonates such assodium carbonate, potassium carbonate, and cesium carbonate; hydroxidessuch as sodium hydroxide, potassium hydroxide, and tetramethylammoniumhydroxide; metal hydrides such as sodium hydride and potassium hydride;organometallic compounds such as butyllithium and ethyl magnesiumbromide; and metal amides such as lithium diisopropylamide. Depending onreaction conditions, any of the foregoing bases may be selected and usedalone or in admixture. An amount of the base used is desirably 0.3 to 20moles, and more desirably 0.8 to 10 moles per mole of hemiacetalcompound (1′). Examples of the transition metal salt used herein includelead carbonate, cadmium carbonate, silver carbonate, lead oxide, cadmiumoxide, silver oxide, and silver nitrate. Depending on reactionconditions, any of the foregoing salts may be selected and used alone orin admixture. The base and transition metal salt may be used alone or inadmixture.

To the reaction system, a catalyst may be added in order to acceleratethe reaction rate. Suitable catalysts include iodides such as sodiumiodide, lithium iodide, and tetrabutylammonium iodide, and bromides suchas sodium bromide, lithium bromide and tetrabutylammonium bromide. Whenused, an amount of the catalyst added is desirably 0.001 to 2 moles, andmore desirably 0.005 to 0.5 mole per mole of hemiacetal compound (1′).

It is desirable from the standpoint of yield that the reaction time isdetermined so as to drive the reaction to completion by monitoring thereaction process by gas chromatography (GC) or thin-layer chromatography(TLC). Usually, the reaction time is about 0.1 to 100 hours. From thereaction mixture, the desired acetal compound (1) is recovered throughan ordinary aqueous workup. If necessary, the compound may be purifiedby a standard technique such as distillation, chromatography orrecrystallization. Alternatively, without aqueous workup, the reactionsolution may be purified directly or after the salt resulting fromreaction is filtered off. Although the above description refers tocompound (1) as a typical example, the synthesis method described hereinis applicable to the preparation of any of compounds (2), (3), (4),(2-1), (3-1), (4-1), (2-2), (3-2), and (4-2).

For example, compounds of formulae (2), (3) and (4) are synthesized asfollows.

Herein, R¹, R^(2a), R^(2b), R^(3a), R^(3b), R⁴, R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a) and R^(9b) are as definedabove.

From the fluorinated monomers of cyclic acetal structure represented byformulae (1), (2), (3), (4), (2-1), (3-1), (4-1), (2-2), (3-2), and(4-2), homopolymers may be prepared or copolymers may be preparedthrough copolymerization with one or more other polymerizable monomers,both by a standard polymerization technique such as radicalpolymerization, anionic polymerization or cationic polymerization. As tothe preparation, any well-known method and conditions for thepolymerization of a polymerizable unsaturated bond, especiallypolymerizable double bond may be selected.

The fluorinated monomer of the invention is useful as a monomer forproducing an additive polymer in immersion lithography resistcompositions, and a polymer in a protective coating material to beformed on a resist film of immersion lithography resist compositions.

Polymer

The invention also provides a polymer or high-molecular-weight compoundcomprising recurring units represented by one of the general formulae(5) to (7).

Herein R¹ is hydrogen, methyl or trifluoromethyl. X is a structurehaving the general formula (X-1), (X-2) or (X-3), Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3), and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3).

In formula (X-1), (Y-1) and (Z-1), R^(2a), R^(2b), R^(3a), and R^(3b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(2a), R^(2b), R^(3a), and R^(3b) may bond together to form a ringwith the carbon atom to which they are attached. The structure (X-1),(Y-1) or (Z-1) is linked to the —(C═O)—O— linkage in recurring unit (5),(6) or (7) via any one of R^(2a), R^(2b), R^(3a), and R^(3b).

In formula (X-2), (Y-2) and (Z-2) , R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b) are each independently a single bond, hydrogen,hydroxyl, halogen, or a straight, branched or cyclic monovalent C₁-C₁₅organic group, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) may bond together to form a ring with the carbon atom to whichthey are attached. The structure (X-2), (Y-2) or (Z-2) is linked to the—(C═O)—O— linkage in recurring unit (5), (6) or (7) via any one ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b).

In formula (X-3), (Y-3) and (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached. The structure (X-3),(Y-3) or (Z-3) is linked to the —(C═O)—O— linkage in recurring unit (5),(6) or (7) via any one of R^(8a), R^(8b), R^(9a), and R^(9b).

R⁴ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which atleast one hydrogen atom may be substituted by a halogen atom or at leastone methylene moiety may be substituted by an oxygen atom or carbonylgroup. R¹⁰ is a straight, branched or cyclic C₁-C₁₉ alkyl group in whichat least one hydrogen atom may be substituted by a halogen atom or atleast one methylene moiety may be substituted by an oxygen atom orcarbonyl group. R¹¹ is hydrogen or a straight, branched or cyclic C₁-C₁₈alkyl group in which at least one hydrogen atom may be substituted by ahalogen atom or at least one methylene moiety may be substituted by anoxygen atom or carbonyl group, R¹² is a straight, branched or cyclicC₁-C₁₉ alkyl group in which at least one hydrogen atom may besubstituted by a halogen atom or at least one methylene moiety may besubstituted by an oxygen atom or carbonyl group, or R¹¹ and R¹² may bondtogether to form a cyclic structure with the carbon and oxygen atoms towhich they are attached.

It is noted that when the structure of X, Y or Z is linked to the—(C═O)—O— linkage in recurring unit (5), (6) or (7) via a linking groupwhich is any one of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b),R^(6a), R^(6b), R^(7a), R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), thelinking group is an organic group as defined above, but having a valencebond as a result of one hydrogen atom being eliminated therefrom.

More specifically, examples of the straight, branched or cyclic C₁-C₁₅monovalent organic groups represented by R^(2a), R^(2b), R^(3a) andR^(3b) in formulae (X-1), (Y-1) and (Z-1) are as illustrated above, andR^(5a) through R^(9b) are also as illustrated above.

Examples of R⁴ are as illustrated above although preferred examples are—CO—R¹⁰ and —CH(R¹¹)—OR¹². Examples of the alkyl groups of R¹⁰, R¹¹ andR¹² are as illustrated above.

Illustrative examples of recurring units of formulae (5), (6) and (7)are given below, but not limited thereto.

Herein R¹ is as illustrated above.

In the polymers, recurring units of formula (5), (6) or (7) exert aneffect in water repellency and water sliding property. In the polymercomprising recurring units of formula (5), (6) or (7), it is easy tocontrol structural parameters including carbon chain length, branchingdegree and fluorine number in R⁴ in formula (5), R¹⁰ in formula (6), orR¹¹ and R¹² in formula (7). This ensures preparation of a polymer havingappropriate water repellency and water sliding property as required ofthe resist protective coating material.

The polymer may be endowed with alkaline hydrolyzability if necessary.In such a case, inclusion of recurring units of formula (6) ispreferred. Hemiacetal hydroxyl group has a higher acidity than alcoholichydroxyl group. Since the ester bond in formula (6) is an ester betweena carboxylic acid and a hemiacetal hydroxyl group having a furtherhigher acidity as a result of five fluorine atoms bonding to vicinalcarbon atoms, and thus regarded as mixed acid anhydride, this ester ishighly susceptible to alkaline hydrolysis as compared with esters ofcarboxylic acid with ordinary alcohol. It is thus believed that thisester is readily hydrolyzed with an alkaline developer, for example.

Also the polymer may be endowed with acid lability if necessary. In sucha case, inclusion of recurring units of formula (7) is preferred. It isbelieved that the acid labile acetal structure (—O—CH(R¹¹)—OR¹²)included in formula (7) will be readily decomposed if an acid generatedby an acid generator is present in proximity thereto.

When the ester bond in formula (6) is hydrolyzed or the acetal structurein formula (7) is decomposed, a highly hydrophilic hemiacetal structureforms whereby the contact angle at polymer surface is reduced,especially the contact angle at polymer surface after development isreduced, contributing to a reduction of blob defects.

In the embodiment wherein the polymer is for use in protective coatingmaterial, a polymer having improved water repellency, water slidingproperty, alkaline solubility and contact angle after development can beproduced by incorporating recurring units of one or more type selectedfrom formulae (8a) to (8f) in addition to the recurring units of formula(5), (6) or (7).

Herein R¹ is hydrogen, methyl or trifluoromethyl. R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached. R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group.R¹⁵ is a straight, branched or cyclic C₁-C₁₅ fluoroalkyl group. R¹⁶ isan acid labile group.

In formulae (8a) to (8f), examples of the straight, branched or cyclicC₁-C₁₅ alkyl groups represented by R^(13a), R^(13b) and R¹⁴ includemethyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,tert-amyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl,cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl,cyclopentylbutyl, cvclohexvlmethyl, cyclohexylethyl, cyclohexylbutyl,and adamantyl. R^(13a) and R^(13b) may bond together to form anon-aromatic ring with the carbon atom to which they are attached. Inthis case, R^(13a) and R^(13b) each are an alkylene group, examples ofwhich are the foregoing alkyl groups with one hydrogen atom eliminated,and exemplary rings include cyclopentyl and cyclohexyl.

The C₁-C₁₅ fluoroalkyl group represented by R¹⁴ and R¹⁵ are theforegoing alkyl groups in which some or all hydrogen atoms aresubstituted by fluorine atoms. Examples include trifluoromethyl,2,2,2-trifluoroethyl, 3,3,3-trifluoropropyl,1,1,2,2,3,3,3-heptafluoropropyl, 1H,1H,3H-tetrafluoropropyl,1H,1H,5H-octafluoropentyl, 1H,1H,7H-dodecafluoroheptyl,2-(perfluorobutyl)ethyl, 2-(perfluorohexyl)ethyl,2-(perfluorooctyl)ethyl, and 2-(perfluorodecyl)ethyl.

The acid labile group represented by R¹⁴ and R¹⁶ may be selected from avariety of such groups. Examples of the acid labile group are groups ofthe following general formulae (L1) to (L4), tertiary alkyl groups of 4to 20 carbon atoms, preferably 4 to 15 carbon atoms, trialkylsilylgroups in which each alkyl moiety has 1 to 6 carbon atoms, and oxoalkylgroups of 4 to 20 carbon atoms.

Herein R^(L01) and R^(L02) are hydrogen or straight, branched or cyclicalkyl groups of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms.R^(L03) is a monovalent hydrocarbon group of 1 to 18 carbon atoms,preferably 1 to 10 carbon atoms, which may contain a heteroatom such asoxygen, examples of which include unsubstituted straight, branched orcyclic alkyl groups and substituted forms of such alkyl groups in whichsome hydrogen atoms are replaced by hydroxyl, alkoxy, oxo, amino,alkylamino or the like. R^(L04) is a tertiary alkyl group of 4 to 20carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group inwhich each alkyl moiety has 1 to 6 carbon atoms, an oxoalkyl group of 4to 20 carbon atoms, or a group of formula (L1). R^(L05) is an optionallysubstituted, straight, branched or cyclic C₁-C₁₀ alkyl group or anoptionally substituted C₆-C₂₀ aryl group. R^(L06) is an optionallysubstituted, straight, branched or cyclic C₁-C¹⁰ alkyl group or anoptionally substituted C₆-C₂₀ aryl group. R^(L07) to R^(L16)independently represent hydrogen or monovalent hydrocarbon groups of 1to 15 carbon atoms. Letter y is an integer of 0 to 6, m is equal to 0 or1, n is equal to 0, 1, 2 or 3, and 2m+n is equal to 2 or 3. The brokenline denotes a valence bond.

In formula (L1), exemplary groups of R^(L01) and R^(L02) include methyl,ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl,cyclohexyl, 2-ethylhexyl, n-octyl, and adamantyl. R^(L03) is amonovalent hydrocarbon group of 1 to 18 carbon atoms, preferably 1 to 10carbon atoms, which may contain a heteroatom such as oxygen, examples ofwhich include unsubstituted straight, branched or cyclic alkyl groupsand substituted forms of such alkyl groups in which some hydrogen atomsare replaced by hydroxyl, alkoxy, oxo, amino, alkylamino or the like.Illustrative examples of the straight, branched or cyclic alkyl groupsare as exemplified above for R^(L01) and R^(L02), and examples of thesubstituted alkyl groups are as shown below.

A pair of R^(L01) and R^(L02), R^(L01)and R^(L03), or R^(L02) andR^(L03) may bond together to form a ring with carbon and oxygen atoms towhich they are attached. Each of ring-forming R^(L01), R^(L02) andR^(L03) is a straight or branched alkylene group of 1 to 18 carbonatoms, preferably 1 to 10 carbon atoms when they form a ring.

In formula (L2), exemplary tertiary alkyl groups of R^(L04) aretert-butyl, tert-amyl, 1,1-diethylpropyl, 2-cyclopentylpropan-2-yl,2-cyclohexylpropan-2-yl, 2-(bicyclo[2.2.1]heptan-2-yl)propan-2-yl,2-(adamantan-1-yl)propan-2-yl, 1-ethylcyclopentyl, 1-butylcyclopentyl,1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl,1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, andthe like. Exemplary trialkylsilyl groups are trimethylsilyl,triethylsilyl, and dimethyl-tert-butylsilyl. Exemplary oxoalkyl groupsare 3-oxocyclohexyl, 4-methyl-2-oxooxan-4-yl, and5-methyl-2-oxooxolan-5-yl.

In formula (L3), examples of the optionally substituted alkyl groups ofR^(L05) include straight, branched or cyclic alkyl groups such asmethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,tert-amyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl, andbicyclo[2.2.1]heptyl, and substituted forms of such groups in which somehydrogen atoms are replaced by hydroxyl, alkoxy, carboxy,alkoxycarbonyl, oxo, amino, alkylamino, cyano, mercapto, alkylthio,sulfo or other groups or in which some methylene groups are replaced byoxygen or sulfur atoms. Examples of optionally substituted C₆-C₂₀ arylgroups include phenyl, methylphenyl, naphthyl, anthryl, phenanthryl, andpyrenyl.

In formula (L4), examples of optionally substituted, straight, branchedor cyclic C₁-C₁₀ alkyl groups and optionally substituted C₆-C₂₀ arylgroups of R^(L06) are the same as exemplified for R^(L05). ExemplaryC₁-C₁₅ hydrocarbon groups of R^(L07) to R^(L16) are straight, branchedor cyclic alkyl groups such as methyl, ethyl, propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, n-octyl,n-nonyl, n-decyl, cyclopentyl, cyclohexyl, cyclopentylmethyl,cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyland cyclohexylbutyl, and substituted forms of these groups in which somehydrogen atoms are replaced by hydroxyl, alkoxy, carboxy,alkoxycarbonyl, oxo, amino, alkylamino, cyano, mercapto, alkylthio,sulfo or other groups. Alternatively, two of R^(L07) to R^(L16) may bondtogether to form a ring with the carbon atom(s) to which they areattached (for example, a pair of R^(L07) and R^(L08), R^(L07) andR^(L09), R^(L08) and R^(L10), R^(L09) and R^(L10), R^(L11)and R^(L12),R^(L13) and R^(L14), or a similar pair form a ring). Each of R^(L07) toR^(L16) represents a divalent C₁-C₁₅ hydrocarbon group when they form aring, examples of which are those exemplified above for the monovalenthydrocarbon groups, with one hydrogen atom being eliminated. Two ofR^(L07) to R^(L16) which are attached to vicinal carbon atoms may bondtogether directly to form a double bond (for example, a pair of R^(L07)and R^(L09), R^(L09) and R^(L15), R^(L13) and R^(L15), or a similarpair).

Of the acid labile groups of formula (L1), the straight and branchedones are exemplified by the following groups.

Of the acid labile groups of formula (L1), the cyclic ones are, forexample, tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl,tetrahydropyran-2-yl, and 2-methyltetrahydropyran-2-yl.

Examples of the acid labile groups of formula (L2) includetert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-amyloxycarbonyl,tert-amyloxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl,1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycarbonyl,1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyloxycarbonyl,1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl,2-tetrahydropyranyloxycarbonylmethyl, and2-tetrahydrofuranyloxycarbonylmethyl.

Examples of the acid labile groups of formula (L3) include1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl,1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-sec-butylcyclopentyl,1-cyclohexylcyclopentyl, 1-(4-methoxy-n-butyl)cyclopentyl,1-(bicyclo[2.2.1]heptan-2-yl)cyclopentyl,1-(7-oxabicyclo[2.2.1]heptan-2-yl)cyclopentyl, 1-methylcyclohexyl,1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl,3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl, and3-ethyl-1-cyclohexen-3-yl.

Of the acid labile groups of formula (L4), those groups of the followingformulae (L4-1) to (L4-4) are preferred.

In formulas (L4-1) to (L4-4), the broken line denotes a bonding site anddirection. R^(L41) is each independently a monovalent hydrocarbon group,typically a straight, branched or cyclic C₁-C₁₀ alkyl group, such asmethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,tert-amyl, n-pentyl, n-hexyl, cyclopentyl and cyclohexyl.

For formulas (L4-1) to (L4-4), there can exist enantiomers anddiastereomers. Each of formulae (L4-1) to (L4-4) collectively representsall such stereoisomers. Such stereoisomers may be used alone or inadmixture.

For example, the general formula (L4-3) represents one or a mixture oftwo selected from groups having the following general formulas (L4-3-1)and (L4-3-2).

Note that R^(L41) is as defined above.

Similarly, the general formula (L4-4) represents one or a mixture of twoor more selected from groups having the following general formulas(L4-4-1) to (L4-4-4).

Note that R^(L41) is as defined above.

Each of formulas (L4-1) to (L4-4), (L4-3-1) and (L4-3-2), and (L4-4-1)to (L4-4-4) collectively represents an enantiomer thereof and a mixtureof enantiomers.

It is noted that in the above formulas (L4-1) to (L4-4), (L4-3-1) and(L4-3-2), and (L4-4-1) to (L4-4-4), the bond direction is on the exoside relative to the bicyclo[2.2.1]heptane ring, which ensures highreactivity for acid catalyzed elimination reaction (see JP-A2000-336121). In preparing these monomers having a tertiary exo-alkylgroup of bicyclo[2.2.1]heptane structure as a substituent group, theremay be contained monomers substituted with an endo-alkyl group asrepresented by the following formulas (L4-1-endo) to (L4-4-endo). Forgood reactivity, an exo proportion of at least 50 mol % is preferred,with an exo proportion of at least 80 mol % being more preferred.

Note that R^(L41) is as defined above.

Illustrative examples of the acid labile group of formula (L4) are givenbelow.

Examples of the tertiary C₄-C₂₀ alkyl groups, trialkylsilyl groups inwhich each alkyl moiety has 1 to 6 carbon atoms, and C₄-C₂₀ oxoalkylgroups, represented by R³, are as exemplified for R^(L04) and the like.

Illustrative examples of the recurring units of formulae (8a) to (8f)are given below, but not limited thereto.

Herein R¹ is as defined above.

Although the polymer comprising recurring units of formulae (5) to (7)in combination with recurring units of formulae (8a) to (8f) exertssatisfactory performance, recurring units of one or more types selectedfrom formulae (12a) to (12e), (13a) to (13e), (14a) to (14c), and (15a)to (15c) may be further incorporated therein for the purposes ofimparting further water repellency and water sliding property, andcontrolling alkaline solubility and developer affinity.

Herein R¹⁷ is a C₁-C₁₅ alkyl or fluoroalkyl group, R¹⁸ is an adhesivegroup, R¹⁹ is an acid labile group, R²⁰ is a single bond or divalentC₁-C₁₅ organic group, and R²¹ and R²² each are hydrogen, methyl ortrifluoromethyl.

Examples of the C₁-C₁₅ alkyl or fluoroalkyl group represented by R¹⁷ arethe same as illustrated for formulae (8a) to (8f).

The adhesive group represented by R¹⁸ may be selected from a variety ofsuch groups, typically those groups shown below.

Herein, the broken line designates a valence bond.

The acid labile group represented by R¹⁹ may be selected from thosegroups illustrated for R¹⁴ and R¹⁶. Suitable divalent C₁-C₁₅ organicgroups represented by R²⁰ include the above-illustrated alkyl groupswith one hydrogen atom eliminated (e.g., methylene and ethylene) andgroups of the following formulae.

Herein, the broken line designates a valence bond.

The polymer of the invention exerts satisfactory performance even whenused alone. In a preferred embodiment, a second polymer comprisingrecurring units of at least one type selected from formulae (9) to (11)may be used in blend with the inventive polymer for the purposes ofimparting further water repellency and water sliding property, andcontrolling alkaline solubility and developer affinity.

Herein R^(31a) to R^(31c) are hydrogen or methyl. R³² is a single bond,C₁-C₄ alkylene, phenylene, —C(═O)—O—, or —C(═O)—NH—. R³³ is a singlebond or a straight, branched or cyclic C₁-C₈ alkylene group. R^(34a) toR^(34d) and R^(36a) to R^(36c) are each independently hydrogen, astraight, branched or cyclic C₁-C₁₂ alkyl, alkenyl, oxoalkyl oroxoalkenyl group, C₆-C₂₀ aryl group, or C₇-C₁₂ aralkyl or aryloxoalkylgroup, in which some or all hydrogen atoms may be substituted by alkoxygroups, R^(34a) to R^(34d) and R^(36a) to R^(36c) may contain a nitrogenatom, ether group, ester group, hydroxyl group or carboxyl grouptherein, any two of R^(34a) to R^(34d) and R^(36a) to R^(36c) may bondtogether to form a ring with the nitrogen atom to which they areattached, and when they form a ring, they are each independently aC₃-C₁₅ alkylene or a hetero-aromatic ring having the nitrogen atomtherein. R³⁵ is a straight, branched or cyclic C₁-C₈ alkylene group. R³⁷is a straight, branched or cyclic C₁-C₂₀ alkyl group which may containcarbonyl, ester, ether or halogen, or a C₆-C₁₅ aryl group which maycontain carbonyl, ester, ether, halogen, or C₁-C₁₅ alkyl or fluoroalkyl.R^(38a) and R^(38b) are hydrogen or a straight, branched or cyclicC₁-C₁₅ alkyl group, or R^(38a) and R^(38b) may bond together to form aring with the carbon atom to which they are attached.

Examples of the C₁-C₄ alkylene group represented by R³² include methyl,ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and tert-butyl groups,with one hydrogen atom eliminated.

Examples of the straight, branched or cyclic C₁-C₈ alkylene grouprepresented by R³³ and R³⁵ include methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl,cyclohexylmethyl and cyclohexylethyl groups, with one hydrogen atomeliminated.

In formula (9), the ammonium salt (cationic moiety) formed by R^(34a) toR^(34d) is obtained from neutralization reaction of a correspondingamine compound. Suitable amine compounds include primary, secondary andtertiary aliphatic amines, mixed amines, aromatic amines, heterocyclicamines, nitrogen-containing compound having carboxyl group,nitrogen-containing compound having sulfonyl group, nitrogen-containingcompound having hydroxyl group, nitrogen-containing compound havinghydroxyphenyl group, amides, imides, and carbamates. Illustrativeexamples of the amine compound which can be used herein include thosedescribed in JP-A 2008-111103, paragraphs [0146] to [0164].

Examples of R^(36a) to R^(36c) and R³⁷ will become apparent fromillustrative examples of formula (10).

Examples of the C₁-C₁₅ alkyl group represented by R^(38a) and R^(39b)are the same as illustrated for formulae (8a) to (8f).

Illustrative examples of the recurring units of formula (9) are givenbelow, but not limited thereto.

Herein R^(31a) and R^(34a) to R^(34d) are as defined above.

Illustrative examples of the recurring units of formula (10) are givenbelow, but not limited thereto.

Herein R^(31b) and R³⁷ are as defined above.

Examples of the sulfonic acid salt used in the recurring units offormula (10) include fluoroalkylsulfonates such as triflate,1,1,1-trifluoroethanesulfonate and nonafluorobutanesulfonate;arylsulfonates such as tosylate, benzenesulfonate,4-fluorobenzenesulfonate, 1,2,3,4,5-pentafluorobenzenesulfonate,xylenesulfonate, mesitylenesulfonate, p-t-butylbenzenesulfonate,naphthalenesulfonate, anthracenesulfonate, and pyrenesulfonate; andalkylsulfonates such as mesylate, butanesulfonate, octanesulfonate,camphorsulfonate, adamantanesulfonate, norbornanesulfonate,cyclohexylsulfonate, cyclopentanesulfonate, cyclobutanesulfonate,cyclopropanesulfonate, and dodecylbenzenesulfonate.

Illustrative, non-limiting examples of the recurring units of formula(11) are given below.

Herein R^(31c) is as defined above.

Although the polymer comprising recurring units of formulae (9) to (11)exerts satisfactory performance even when it has only a combination ofrecurring units of formulae (9) to (11), recurring units of one or moretypes selected from formulae (12a) to (12e), (13a) to (13e), (14a) to(14c), and (15a) to (15c) may be further incorporated therein for thepurposes of imparting further water repellency and water slidingproperty, and controlling alkaline solubility and developer affinity.

Polymer Synthesis

For convenience of description, the polymer comprising recurring unitsof formulae (5) to (7) and optionally recurring units of formulae (8a)to (8f) is referred to as polymer P1, and the second or blending polymercomprising recurring units of formulae (9) to (11) is referred to aspolymer P2.

The polymers P1 and P2 used herein may be synthesized by generalpolymerization processes including radical polymerizataion usinginitiators such as 2,2′-azobisisobutyronitrile (AIBN), and ionic (oranionic) polymerization using alkyllithium or the like. Thepolymerization may be carried out by a standard technique. Preferablythe polymers are prepared by radical polymerization while thepolymerization conditions may be determined in accordance with the typeand amount of initiator, temperature, pressure, concentration, solvent,additives, and the like.

Examples of the radical polymerization initiator used herein include azocompounds such as 2,2′-azobisisobutyronitrile (AIBN),2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2,4,4-trimethylpentane), and dimethyl2,2′-azobis(isobutyrate); peroxides such as tert-butylperoxypivalate,lauroyl peroxide, benzoyl peroxide, and tert-butylperoxylaurate;water-soluble polymerization initiators such as potassium persulfate;and redox initiators comprising a peroxide (e.g., potassium persulfateor hydrogen peroxide) combined with a reducing agent (e.g., sodiumsulfite). Although the amount of polymerization initiator used may varywith its type and other polymerization conditions, it is generally usedin an amount of 0.001 to 10 mol %, and preferably 0.01 to 6 mol % basedon the total moles of monomers to be polymerized.

During the synthesis of polymer P1 or P2, any known chain transfer agentsuch as dodecyl mercaptan or 2-mercaptoethanol may be added formolecular weight control purpose. The amount of chain transfer agentadded is preferably 0.01 to 10 mol % based on the total moles ofmonomers to be polymerized.

Polymer P1 may be synthesized by combining suitable monomers selectedfrom polymerizable monomers corresponding to recurring units of formulae(5) to (7), (8a) to (8f), (12a) to (12e), (13a) to (13e), (14a) to(14c), and (15a) to (15c), adding an initiator and chain transfer agentto the monomer mixture, and effecting polymerization. Similarly, polymerP2 may be synthesized by combining suitable monomers selected frompolymerizable monomers corresponding to recurring units of formulae (9)to (11), adding an initiator and chain transfer agent to the monomermixture, and effecting polymerization.

In polymer P1 wherein U11 stands for a total molar number of a monomeror monomers corresponding to units of formulae (5) to (7), U12 standsfor a total molar number of a monomer or monomers corresponding to unitsof formulae (8a) to (8f), and U13 stands for a total molar number of amonomer or monomers corresponding to units of formulae (12a) to (12e),(13a) to (13e), (14a) to (14c), and (15a) to (15c), with the provisothat U11+U124-U13=U1, values of U11, U12, and U13 are preferablydetermined so as to meet:

0<U11/U1<1, more preferably 0.1≦U11/U1≦0.7, even more preferably0.2≦U11/U1≦0.6,

0≦U12/U1<1, more preferably 0.3≦U12/U1≦0.9, even more preferably0.4≦U12/U1≦0.8, and

0≦U13/U1<1, more preferably 0≦U13/U1≦0.5, even more preferably0≦U13/U1≦0.3,

with the proviso that U1≦100 mol %.

In polymer P2 wherein U21 stands for a total molar number of amonomer(s) corresponding to units of formula (9), U22 stands for a totalmolar number of a monomer(s) corresponding to units of formula (10), U23stands for a total molar number of a monomer(s) corresponding to unitsof formula (11), and U24 stands for a total molar number of a monomer(s)corresponding to units of formulae (12a) to (12e), (13a) to (13e), (14a)to (14c), and (15a) to (15c), with the proviso that U21+U22+U23+U24=U2,values of U21, U22, U23, and U24 are preferably determined so as tomeet:

0≦U21/U2<1, more preferably 0≦U21/U2≦0.5, even more preferably0≦U21/U2≦0.3,

0≦U22/U2<1, more preferably 0≦U22/U2≦0.5, even more preferably0≦U22/U2≦0.3,

0<U23/U2<1, more preferably 0.5≦U23/U2<1, even more preferably0.7≦U23/U2<1, and

0≦U24/U2<1, more preferably 0≦U24/U2<0.5, even more preferably0≦U24/U2<0.3,

with the proviso that U2≦100 mol %.

In conducting polymerization, a solvent may be used if necessary. Anysolvent may be used as long as it does not interfere with the desiredpolymerization reaction. Typical solvents used herein include esterssuch as ethyl acetate, n-butyl acetate, and γ-butyrolactone; ketonessuch as acetone, methyl ethyl ketone, and methyl isobutyl ketone;

aliphatic or aromatic hydrocarbons such as toluene, xylene andcyclohexane; alcohols such as isopropyl alcohol and ethylene glycolmonomethyl ether; and ether solvents such as diethyl ether, dioxane, andtetrahydrofuran, which may be used alone or in admixture. Although theamount of solvent used may vary with the desired degree ofpolymerization (or molecular weight), the amount of initiator added, andother polymerization conditions such as polymerization temperature, itis generally used in such an amount as to provide a concentration of 0.1to 95% by weight, preferably 5 to 90% by weight of monomers to bepolymerized.

Although the temperature of the polymerization reaction may vary withthe identity of polymerization initiator or the boiling point ofsolvent, it is preferably in the range of 20 to 200° C., and morepreferably 50 to 140° C. Any desired reactor or vessel may be used forthe polymerization reaction.

From the solution or dispersion of the polymer thus synthesized, theorganic solvent or water serving as the reaction medium is removed byany well-known techniques. Suitable techniques include, for example,re-precipitation followed by filtration, and heat distillation undervacuum.

Desirably polymers P1 and P2 have a weight average molecular weight (Mw)of 1,000 to 500,000, and especially 2,000 to 30,000, as determined bygel permeation chromatography (GPC) using polystyrene standards. This isbecause a polymer with too low a Mw may be miscible with the resistmaterial or more dissolvable in water whereas too high a Mw mayinterfere with film formation after spin coating and lead to a declineof alkali solubility.

In polymers P1 and P2, R⁴ in formula (5), R¹⁴ in formulae (8a), (8b),and (8e), and R¹⁹ in formula (12c) and (13c) may be introduced bypost-protection reaction. Specifically, a polymer may be synthesized bypolymerizing a monomer wherein R⁴, R¹⁴ and R¹⁹ are hydrogen tosynthesize an intermediate polymer, then effecting post-protectionreaction to substitute R⁴, R¹⁴ and R¹⁹ (as defined above) for some orall hydroxyl groups in the intermediate polymer.

The desired (post-protected) polymer is obtainable throughpost-protection reaction by reacting the intermediate polymer with abase in an amount of 1 to 2 equivalents relative to the desired degreeof substitution of hydroxyl groups, and then with R—X (wherein R is R⁴,R¹⁴ and R¹⁹ as mentioned above and X is chlorine, bromine or iodine) inan amount of 1 to 2 equivalents relative to the base.

The post-protection reaction may be effected in a solvent, which isselected from hydrocarbons such as benzene and toluene, and ethers suchas dibutyl ether, diethylene glycol diethyl ether, diethylene glycoldimethyl ether, tetrahydrofuran and 1,4-dioxane, alone or in admixture.Suitable bases used herein include, but are not limited to, sodiumhydride, n-butyllithium, lithium diisopropylamide, triethylamine, andpyridine.

In polymer P2, the ammonium salt in recurring units of formula (9) maybe obtained from neutralization reaction of a (meth)acrylate having asulfo pendant group with a corresponding amine or ion exchange reactionthereof with an ammonium salt having the following general formula.

Herein R^(34a) to R^(34d) are as defined above, L⁻ is OH⁻, Cl⁻, Br⁻, I⁻,R³⁹CO₂ ⁻, or NO₃ ⁻, and R³⁹ is hydrogen or a monovalent organic group.

In polymer P2, recurring units of formula (9) may be introduced byeffecting neutralization reaction or ion exchange reaction at themonomer stage or after polymer synthesis. In the latter case, if theamount of amine added is small, an amine salt is not uniformly formedwithin polymer units which may cause local bridge defects upon patternformation. To avoid such inconvenience, it is preferred thatneutralization or ion exchange reaction be carried out in a monomerform, and this be followed by polymerization using the resulting monomerhaving a sulfonic acid amine salt uniformly distributed.

In polymer P2 wherein recurring units of formula (10) are introduced,those units containing a tertiary or lower ammonium salt may be obtainedfrom neutralization reaction of a (meth)acrylate having an amino pendantgroup with a corresponding sulfonic acid. Those units containing aquaternary ammonium salt may be obtained from ion exchange reaction asdescribed above. As in the case of recurring units of formula (9),neutralization reaction or ion exchange reaction may be effected eitherat the monomer stage or after polymer synthesis.

With respect to the recurring units of formula (9), a degree ofneutralization between sulfo group and amine compound in an overallpolymer may be such that with a less amine equivalent, sulfonic acidresidues are present or inversely, amine is in excess. Where sulfonicacid residues are available, the protective coating, when combined witha photoresist, is effective for preventing bridges between features of aresist pattern after development. On the other hand, where an excess ofamine is available, the protective coating is effective for improvingthe rectangularity of a resist pattern. With these considerations, theamounts of sulfo group and amine may be adjusted as appropriate whilemonitoring a resist pattern after development. The same applies to therecurring units of formula (10).

Protective Coating Composition

In one embodiment, the invention provides a resist protective coatingcomposition comprising the polymer P1 defined above. Polymer P1comprises recurring units of formula (5), (6) or (7) which contain afluorinated hemiacetal structure having a protected hydroxyl group. By achoice of resin structure, it is possible to tailor any of propertiesincluding water repellency, water sliding property, lipophilicity, acidlability, hydrolyzability, and alkaline solubility.

Since polymer P2 contains a hydrophilic sulfonic acid amine salt inrecurring units, it tends to segregate on the resist side after spincoating. As a result, the resist surface after development becomeshydrophilic, inhibiting blob defects. If a polymer having only sulfogroups is used as a protective coating material, part of the quencher inthe resist film migrates to the protective coating layer. In casequencher migration occurs, the quencher concentration at the outermostsurface of the resist film lowers, and the resist pattern afterdevelopment may be concomitantly thinned and as a result, weakened inetch resistance. In contrast, a protective coating layer of polymer P2in which a sulfonic acid amine salt is present prohibits quenchermigration as mentioned above and ensures to form a rectangular resistpattern.

When a blend of polymers P1 and P2 is used, layer separation occursduring spin coating such that polymer featuring water repellency andwater sliding property segregates in a protective coating upper layerand polymer P2 featuring hydrophilicity segregates in a protectivecoating lower layer on top of the resist film. This results in aprotective coating having improved water repellency and water slidingproperty on the resist surface and effective in inhibiting blob defects.

While polymers P1 and P2 may be mixed at any desired ratio, polymer P1is typically present in a weight ratio of 5 to 95%, preferably 20 to93%, and more preferably 30 to 90% based on the entire resin.

Typically a blend of polymers P1 and P2 is used as a base resin in aprotective coating composition while another polymer may be mixedtherewith for the purpose of altering some properties of a protectivecoating such as dynamic physical properties, thermal properties,alkaline solubility, water repellency, and water sliding property. Theother polymer which is mixed is not particularly limited, and any ofwell-known polymers useful in the protective topcoat application may bechosen and mixed in any desired ratio.

Most often, the polymers are dissolved in a suitable solvent to form asolution which is ready for use as the resist protective coatingcomposition. For film formation by spin coating technique, the solventis preferably used in such amounts to provide a concentration of 0.1 to20% by weight, more preferably 0.5 to 10% by weight of the entire resin.

Although the solvent used herein is not particularly limited, thosesolvents in which resist layers are not dissolvable are preferred.Suitable solvents in which resist layers are not dissolvable includenonpolar solvents, for example, higher alcohols of at least 4 carbonatoms, toluene, xylene, anisole, hexane, cyclohexane, decane, andethers. Of these, higher alcohols of at least 4 carbon atoms and ethercompounds of 8 to 12 carbon atoms are most desirable. Examples ofsuitable solvents include, but are not limited to, 1-butyl alcohol,2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol,2-pentanol, 3-pentanol, tert-amyl alcohol, neopentyl alcohol,2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol,cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol,3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2,2-diethyl-1-butanol,2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol,3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol,4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, andcyclohexanol as well as diisopropyl ether, diisobutyl ether, diisopentylether, di-n-pentyl ether, methylcyclopentyl ether, methylcyclohexylether, di-n-butyl ether, di-sec-butyl ether, diisopentyl ether,di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether. Thesesolvents may be used alone or in admixture.

Fluorinated solvents are also preferred because resist layers are notdissolvable therein. Examples include, but are not limited to,2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,3-difluoroanisole,2,4-difluoroanisole, 2,5-difluoroanisole, 5,8-difluoro-1,4-benzodioxane,2,3-difluorobenzyl alcohol, 1,3-difluoro-2-propanol,2′,4′-difluoropropiophenone, 2,4-difluorotoluene, trifluoroacetaldehydeethyl hemiacetal, trifluoroacetamide, trifluoroethanol,2,2,2-trifluoroethyl butyrate, ethyl heptafluorobutyrate, ethylheptafluorobutylacetate, ethyl hexafluoroglutarylmethyl, ethyl3-hydroxy-4,4,4-trifluorobutyrate, ethyl2-methyl-4,4,4-trifluoroacetoacetate, ethyl pentafluorobenzoate, ethylpentafluoropropionate, ethyl pentafluoropropynylacetate, ethylperfluorooctanoate, ethyl 4,4,4-trifluoroacetoacetate, ethyl4,4,4-trifluorobutyrate, ethyl 4,4,4-trifluorocrotonate, ethyltrifluorosulfonate, ethyl 3-(trifluoromethyl)butyrate, ethyltrifluoropyruvate, S-ethyl trifluoroacetate, fluorocyclohexane,2,2,3,3,4,4,4-heptafluoro-1-butanol,1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione,1,1,1,3,5,5,5-heptafluoropentane-2,4-dione,3,3,4,4,5,5,5-heptafluoro-2-pentanol,3,3,4,4,5,5,5-heptafluoro-2-pentanone, isopropyl4,4,4-trifluoroacetoacetate, methyl perfluorodecanoate, methylperfluoro(2-methyl-3-oxahexanoate), methyl perfluorononanoate, methylperfluorooctanoate, methyl 2,3,3,3-tetrafluoropropionate, methyltrifluoroacetoacetate, 1,1,1,2,2,6,6,6-octafluoro-2,4-hexanedione,2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 1H,1H,2H,2H-perfluoro-1-decanol,perfluoro(2,5-dimethyl-3,6-dioxane anionic) acid methyl ester,2H-perfluoro-5-methyl-3,6-dioxanonane,1H,1H,2H,3H,3H-perfluorononane-1,2-diol, 1H,1H,9H-perfluoro-1-nonanol,1H,1H-perfluorooctanol, 1H,1H,2H,2H-perfluorooctanol,2H-perfluoro-5,8,11,14-tetramethyl-3,6,9,12,15-pentaoxa-octadecane,perfluorotributylamine, perfluorotrihexylamine, methylperfluoro-2,5,8-trimethyl-3,6,9-trioxadodecanoate,perfluorotripentylamine, perfluorotripropylamine,1H,1H,2H,3H,3H-perfluoroundecane-1,2-diol, trifluorobutanol,1,1,1-trifluoro-5-methyl-2,4-hexanedione, 1,1,1-trifluoro-2-propanol,3,3,3-trifluoro-1-propanol, 1,1,1-trifluoro-2-propyl acetate,perfluorobutyltetrahydrofuran, perfluorodecalin,perfluoro(1,2-dimethylcyclohexane), perfluoro(1,3-dimethylcyclohexane),propylene glycol trifluoromethyl ether acetate, propylene glycol methylether trifluoromethyl acetate, butyl trifluoromethylacetate, methyl3-trifluoromethoxypropionate, perfluorocyclohexanone, propylene glycoltrifluoromethyl ether, butyl trifluoroacetate,1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione,1,1,1,3,3,3-hexafluoro-2-propanol,1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol,2,2,3,4,4,4-hexafluoro-1-butanol, 2-trifluoromethyl-2-propanol,2,2,3,3-tetrafluoro-1-propanol, 3,3,3-trifluoro-1-propanol, and4,4,4-trifluoro-1-butanol, which may be used alone or in admixture.

In the resist protective coating composition, a basic compound may beused for the purpose of performance amelioration such as pattern profilecorrection. For example, polymer P1 has acidic hydroxyl groups inrecurring units with a possibility that part of the quencher in theresist film migrates to the protective coating layer. As discussedabove, in case quencher migration occurs, the quencher concentration atthe outermost surface of the resist film lowers, and the resist patternafter development is concomitantly thinned. A basic compound ispreviously added to the protective coating composition to avoid suchquencher migration, preventing any degradation of pattern profile.

Preferred basic compounds are nitrogen-containing organic compoundswhich may be used alone or in admixture. Suitable nitrogen-containingorganic compounds include primary, secondary, and tertiary aliphaticamines, mixed amines, aromatic amines, heterocyclic amines,nitrogen-containing compounds having carboxyl group, nitrogen-containingcompounds having sulfonyl group, nitrogen-containing compounds havinghydroxyl group, nitrogen-containing compounds having hydroxyphenylgroup, amide, imide and carbamate derivatives. Illustrative examples aredescribed in JP-A 2008-111103, paragraphs [0149] to [0163]. The basiccompound is preferably used in an amount of 0.001 to 2 parts, morepreferably 0.01 to 1 part by weight per 100 parts by weight of the baseresin.

Pattern Forming Process

The pattern forming process in a preferred embodiment involves at leastthe steps of forming a photoresist film on a substrate, forming aprotective coating on the photoresist film from the resist protectivecoating composition of the invention, exposing the layer structure tolight, and development with a developer.

First a photoresist material is applied onto a substrate and prebaked toform a photoresist film thereon. The protective coating solution is thenapplied onto the photoresist film by spin coating, and prebaked on a hotplate at 50 to 150° C. for 1 to 10 minutes, preferably at 70 to 140° C.for 1 to 5 minutes, to form a protective coating. The protective coatingpreferably has a thickness of 10 to 500 nm.

If the protective coating solution is spin coated onto the surface ofthe resist film which has been wetted with a suitable solvent, theamount of the protective coating solution dispensed can be reduced. Themeans of wetting the resist surface include spin coating and vaporpriming, with the spin coating technique being often employed. Thesolvent used for wetting may be selected from the aforementioned higheralcohols, ethers, and fluorinated solvents in which the resist is notdissolved.

A mask having the desired pattern is then placed over the photoresistfilm, and the film exposed through the mask to an electron beam or tohigh-energy radiation such as deep-UV, excimer laser or x-ray in a doseof 1 to 200 mJ/cm², and preferably 10 to 100 mJ/cm². Light exposure ispreferably by immersion lithography of providing a liquid between theprotective coating and the projection lens, though not limited thereto.The exposure may be either dry exposure in air or nitrogen atmosphere orvacuum exposure as in the case of EB or EUV lithography. In theimmersion lithography, a light source producing emission having awavelength in the range of 180 to 250 nm is preferred, and water ispreferably used as the liquid between the protective coating and thelens.

In the immersion lithography, whether or not the wafer edge and rearside are cleaned and the cleaning technique are important in preventingflowing of water to the wafer rear side and leaching from the substrate.For example, after spin coating, the resist protective coating is bakedat a temperature of 40 to 130° C. for 10 to 300 seconds for evaporatingoff the solvent. In the case of resist layer formation and drylithography, edge cleaning is performed during the spin coating. In thecase of immersion lithography, however, such edge cleaning isundesirable because water may be left on the hydrophilic substratesurface at the edge. It is then recommended to omit edge cleaning duringthe spin coating of the resist protective coating.

Exposure is followed by post-exposure bake (PEB) on a hot plate at 60 to150° C. for 1 to 5 minutes, preferably at 80 to 140° C. for 1 to 3minutes. Sometimes water is left on the protective coating prior to PEB.If PEB is performed in the presence of residual water, water canpenetrate through the protective coating to suck up the acid in theresist, impeding pattern formation. Such inconvenience must be avoidedby fully removing the water on the protective coating prior to PEB. Thewater on the protective coating should be dried or recovered by suitablemeans, for example, spin drying, purging of the protective coatingsurface with dry air or nitrogen, or optimizing the water recoverynozzle configuration on a stage or water recovery process. Additionally,the design and utilization of a material having high water repellencyand water sliding property, typically the protective coating compositionof the invention, offers the advantage of efficient water removal.

After PEB, development is carried out using as the developer an aqueousalkaline solution, such as a 0.1 to 5 wt %, preferably 2 to 3 wt %,aqueous solution of tetramethylammonium hydroxide (TMAH), this beingdone by a conventional method such as dip, puddle, or spray developmentfor a period of 10 to 300 seconds, and preferably 0.5 to 2 minutes. Atypical developer is a 2.38 wt % TMAH aqueous solution. These stepsresult in the formation of the desired pattern on the substrate. Wherethe resist protective coating composition is used, the protectivecoating composition itself exhibits alkaline solubility so that theprotective coating can be stripped at the same time as development.

Where a pattern is formed using the protective coating composition, theresist material of which the underlying resist layer is made is notparticularly limited. The resist type may be either positive or negativeworking and also either a monolayer resist of conventional hydrocarbonor a bilayer (or multilayer) resist containing silicon atoms or thelike.

For KrF lithography resist materials, the preferred base resins arepolyhydroxystyrene or polyhydroxystyrene-(meth)acrylate copolymers inwhich some or all hydrogen atoms of hydroxyl or carboxyl groups arereplaced by acid labile groups.

For ArF lithography resist materials, the preferred base resin has anaromatic-free structure. Illustrative polymers include (meth)acrylicderivative copolymers, norbornene derivative/maleic anhydridealternating copolymers, norbornene derivative/maleicanhydride/(meth)acrylic derivative copolymers, tetracyclododecenederivative/maleic anhydride alternating copolymers, tetracyclododecenederivative/maleic anhydride/(meth)acrylic derivative copolymers,norbornene derivative/maleimide alternating copolymers, norbornenederivative/maleimide/(meth)acrylic derivative copolymers,tetracyclododecene derivative/maleimide derivative alternatingcopolymers, tetracyclododecene derivative/maleimidederivative/(meth)acrylic derivative copolymers, polynorbornenederivatives, and ring-opening metathesis polymerization (ROMP) polymers,and a combination of any.

A polymer comprising recurring units containing aromatic ring could notbe used initially as the ArF lithography resist since it has absorptionat wavelength 193 nm. As the resist film becomes thinner, the influenceof absorption is mitigated, indicating the potential of such a polymerbeing applied to the ArF lithography. Also, since the reflection ofoblique incident light from the substrate increases when a projectionlens has a NA in excess of 1, it is proposed to positively utilize theabsorptive aromatic ring for suppressing reflection from the substrate.Polymers useful in this case include copolymers ofhydroxyvinylnaphthalene, methacrylates containing naphthalene andnaphthol structures on side chains, fluorinated hydroxystyrene,fluoroalkylhydroxystyrene, fluorinated styrene, fluoroalkylstyrene,hexafluoroisopropanolstyrene, and hexafluoroisopropanolindene.

A further aspect of the invention provides a pattern forming processinvolving the steps of forming a photoresist layer on a mask blank,forming a protective coating on the photoresist layer from the resistprotective coating composition of the invention, effecting electron beamexposure in vacuum, and development.

Where the polymer is used as a resist protective coating for use withmask blanks, a photoresist is coated on a mask blank substrate of SiO₂,Cr, CrO, CrN, MoSi or the like before the protective coating compositionis applied to form a protective coating on the resist film. By furtherforming a SOG film and an organic undercoat film between the photoresistand the blank substrate, there is provided a three-layer structure whichis also acceptable herein. Once the protective coating film is formed,the structure is exposed to EB in vacuum using an EB image-writingsystem. The exposure is followed by post-exposure baking (PEB) anddevelopment in an alkaline developer for 10 to 300 seconds.

For the resit material used with mask blanks, novolac resins andhydroxystyrene are often used as the base resin. Those resins in whichalkali-soluble hydroxyl groups are substituted by acid labile groups areused for positive resists while these resins in combination withcrosslinking agents are used for negative resists. Base polymers whichcan be used herein include copolymers of hydroxystyrene with one or moreof (meth)acrylic derivatives, styrene, vinyl naphthalene, vinylanthracene, vinyl pyrene, hydroxyvinyl naphthalene, hydroxyvinylanthracene, indene, hydroxyindene, acenaphthylene, norbornadiene,coumarone, and chromone.

Resist Composition

In a further aspect, the invention provides a resist compositioncomprising (A) a polymer P1 comprising recurring units of formula (5),(6) or (7), (B) a base polymer having a structure derived from lactonering, hydroxyl group and/or maleic anhydride, the base polymer becomingsoluble in alkaline developer under the action of acid, (C) a compoundcapable of generating an acid upon exposure to high-energy radiation,and (D) an organic solvent.

Polymer(s) P1 as component (A) is added to the resist compositionpreferably in a total amount of 0.1 to 50 parts, more preferably 0.5 to10 parts by weight per 100 parts by weight of the base resin (B). Atleast 0.1 phr of polymer P1 is effective in improving the recedingcontact angle with water of photoresist film surface, whereas up to 50phr of polymer P1 forms a photoresist film having a low dissolution ratein alkaline developer and capable of maintaining the height of a finepattern formed therein.

Since polymer P1 comprises recurring units of formula (5), (6) or (7)which contain a fluorinated hemiacetal structure having a protectedhydroxyl group, a choice of resin structure makes it possible to tailorany of properties including water repellency, water sliding property,lipophilicity, acid lability, hydrolyzability, and alkaline solubility.

When polymer P1 is used in admixture with base resin (B) to form aresist film, layer separation occurs during spin coating such thatpolymer P1 segregates in a resist film upper layer. The resulting resistfilm displays improved water repellency and water sliding property onits surface and prevents water-soluble components from being leached outof the resist material.

The resist composition contains (B) a base resin or polymer which has astructure derived from lactone ring and/or hydroxyl group and/or maleicanhydride and becomes soluble in alkaline developer under the action ofacid. The polymers which can serve as the base resin (B) include(meth)acrylates, (α-trifluoromethyl)acrylate/maleic anhydridecopolymers, cycloolefin/maleic anhydride alternating copolymers,polynorbornene, cycloolefin ring-opening metathesis polymerization(ROMP) polymers, hydrogenated cycloolefin ROMP polymers, examples ofwhich are described in JP-A 2008-111103, paragraphs [0072] to [0120].The polymer serving as base resin (B) is not limited to one type and amixture of two or more polymers may be added. The use of plural polymersallows for easy adjustment of resist properties.

In order that the resist composition function as a chemically amplifiedresist composition, (C) a compound capable of generating an acid uponexposure to high-energy radiation, referred to as “photoacid generator”or PAG, may be compounded. The photoacid generator may be any compoundcapable of generating an acid upon exposure of high-energy radiation.Suitable photoacid generators include sulfonium salts, iodonium salts,sulfonyldiazomethane,

N-sulfonyloxyimide, and oxime-O-sulfonate acid generators. Exemplaryacid generators are described in JP-A 2008-111103, paragraphs [0123] to[0138].

The preferred PAGs are those compounds of the general formula (C)-1.

Herein R⁴⁰⁵, R⁴⁰⁶, and R⁴⁰⁷ are each independently hydrogen or astraight, branched or cyclic, monovalent C₁-C₂₀ hydrocarbon group whichmay contain a heteroatom, typically an alkyl or alkoxy group. R⁴⁰⁸ is astraight, branched or cyclic, monovalent C₇-C₃₀ hydrocarbon group whichmay contain a heteroatom.

Examples of the hydrocarbon groups optionally containing a heteroatom,represented by R⁴⁰⁵, R⁴⁰⁶, and R⁴⁰⁷, include methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl,cyclopentyl, cyclohexyl, ethylcyclopentyl, butylcyclopentyl,ethylcyclohexyl, butylcyclohexyl, adamantyl, ethyladamantyl,butyladamantyl, and modified forms of the foregoing in which anycarbon-carbon bond is separated by a hetero-atomic grouping such as —O—,—S—, —SO—, —SO₂—, —NH—, —C(═O)—, —C(═O)O—, or —C(═O)NH—, or any hydrogenatom is replaced by a functional group such as —OH, —NH₂, —CHO, or—CO₂H. Examples of the straight, branched or cyclic, monovalent C₇-C₃₀hydrocarbon groups optionally containing a heteroatom, represented byR⁴⁰⁸, are shown below, but not limited thereto.

Illustrative examples of acid generators (C)-1 are shown below, but notlimited thereto.

In the resist composition, specifically chemically amplified resistcomposition, PAG may be added in any desired amount as long as theobjects of the invention are not compromised. An appropriate amount ofPAG is 0.1 to 10 parts, and more preferably 0.1 to 5 parts by weight per100 parts by weight of the base resin in the composition. Too large anamount of PAG may give rise to problems of degraded resolution andforeign matter upon development and resist film peeling. The PAG may beused alone or in admixture of two or more. The transmittance of theresist film can be controlled by using a PAG having a low transmittanceat the exposure wavelength and adjusting the amount of the PAG added.

It is noted that an acid diffusion controlling function may be providedwhen two or more PAGs are used in admixture provided that one PAG is anonium salt capable of generating a weak acid. Specifically, in a systemusing a mixture of a PAG capable of generating a strong acid (e.g.,fluorinated sulfonic acid) and an onium salt capable of generating aweak acid (e.g., non-fluorinated sulfonic acid or carboxylic acid), ifthe strong acid generated from the PAG upon exposure to high-energyradiation collides with the unreacted onium salt having a weak acidanion, then a salt exchange occurs whereby the weak acid is released andan onium salt having a strong acid anion is formed. In this course, thestrong acid is exchanged into the weak acid having a low catalysis,incurring apparent deactivation of the acid for enabling to control aciddiffusion.

If the PAG capable of generating a strong acid is also an onium salt, anexchange from the strong acid (generated upon exposure to high-energyradiation) to a weak acid as above can take place, but it never happensthat the weak acid (generated upon exposure to high-energy radiation)collides with the unreacted onium salt capable of generating a strongacid to induce a salt exchange. This is because of a likelihood of anonium cation forming an ion pair with a stronger acid anion.

An appropriate amount of PAG added is 0.1 to 20 parts, and morepreferably 0.1 to 10 parts by weight per 100 parts by weight of the baseresin (B) in the composition. As long as PAG is up to 20 phr, theresulting photoresist film has a fully high transmittance and a minimallikelihood of degraded resolution. The PAG may be used alone or inadmixture of two or more. The transmittance of the resist film can becontrolled by using a PAG having a low transmittance at the exposurewavelength and adjusting the amount of the PAG added.

The resist composition may further comprise one or more of (D) anorganic solvent, (E) a basic compound, (F) a dissolution regulator, (G)a surfactant, and (H) an acetylene alcohol derivative.

The organic solvent (D) used herein may be any organic solvent in whichpolymer P1, the base resin, PAG, and other components are soluble.Exemplary solvents are described in JP-A 2008-111103, paragraph [0144].The organic solvents may be used alone or in combinations of two or morethereof. An appropriate amount of the organic solvent used is 200 to3,000 parts, especially 400 to 2,500 parts by weight per 100 parts byweight of the base resin (B). It is recommended to use diethylene glycoldimethyl ether, 1-ethoxy-2-propanol, PGMEA, and mixtures thereof becausethe acid generator is most soluble therein.

As the basic compound (E), nitrogen-containing organic compounds arepreferred and may be used alone or in admixture. Those compounds capableof suppressing the rate of diffusion when the acid generated by the acidgenerator diffuses within the resist film are useful. The inclusion ofnitrogen-containing organic compound holds down the rate of aciddiffusion within the resist film, resulting in better resolution. Inaddition, it suppresses changes in sensitivity following exposure andreduces substrate and environment dependence, as well as improving theexposure latitude and the pattern profile.

Suitable nitrogen-containing organic compounds include primary,secondary, and tertiary aliphatic amines, mixed amines, aromatic amines,heterocyclic amines, nitrogen-containing compounds having carboxylgroup, nitrogen-containing compounds having sulfonyl group,nitrogen-containing compounds having hydroxyl group, nitrogen-containingcompounds having hydroxyphenyl group, amide, imide and carbamatederivatives. Illustrative examples are described in JP-A 2008-111103,paragraphs [0149] to [0163]. The basic compound is preferably used in anamount of 0.001 to 2 parts, more preferably 0.01 to 1 part by weight per100 parts by weight of the base resin (B). At least 0.001 phr achievesthe desired addition effect whereas up to 2 phr minimizes the risk ofreducing sensitivity.

Tertiary amines are especially preferred as the basic compound. Examplesinclude tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine,tri-n-octylamine, N,N-dimethylaniline, triethanolamine,triisopropanolamine, tris(2-methoxymethoxyethyl)amine,tris(2-methoxyethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine,4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane,4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5]eicosane,1,4,10,13-tetraoxa-7,16-diazabicyclooctadecane, 1-aza-12-crown-4,1-aza-15-crown-5, 1-aza-18-crown-6, tris(2-formyloxyethyl)amine,tris(2-acetoxyethyl)amine, tris(2-propionyloxyethyl)amine,tris(2-butyryloxyethyl)amine, tris(2-isobutyryloxyethyl)amine,tris(2-valeryloxyethyl)amine, tris(2-pivaloyloxyethyl)amine,N,N-bis(2-acetoxyethyl)-2-(acetoxyacetoxy)ethylamine,tris(2-methoxycarbonyloxyethyl)amine,tris(2-tert-butoxycarbonyloxyethyl)amine,tris[2-(2-oxopropoxy)ethyl]amine,tris[2-(methoxycarbonylmethyl)oxyethyl]amine,tris[2-(tert-butoxycarbonylmethyloxy)ethyl]amine,tris[2-(cyclohexyloxycarbonylmethyloxy)ethyl]amine,tris(2-methoxycarbonylethyl)amine, tris(2-ethoxycarbonylethyl)amine,tris(2-benzoyloxyethyl)amine, tris[2-(4-methoxybenzoyloxy)ethyl]amine,N,N-bis(2-hydroxyethyl)-2-(methoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(methoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(ethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(ethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-hydroxyethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-acetoxyethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,N,N-bis(2-acetoxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)-ethylamine,N,N-bis(2-acetoxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)-ethylamine,N,N-bis(2-hydroxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxy-carbonyl]ethylamine,N,N-bis(2-acetoxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxy-carbonyl]ethylamine,N,N-bis(2-hydroxyethyl)-2-(4-hydroxybutoxycarbonyl)ethylamine,N,N-bis(2-formyloxyethyl)-2-(4-formyloxybutoxycarbonyl)-ethylamine,N,N-bis(2-formyloxyethyl)-2-(2-formyloxyethoxycarbonyl)-ethylamine,N,N-bis(2-methoxyethyl)-2-(methoxycarbonyl)ethylamine,N-(2-hydroxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-acetoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-hydroxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,N-(2-acetoxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,N-(3-hydroxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(3-acetoxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-methoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-butyl-bis[2-(methoxycarbonyl)ethyl]amine,N-butyl-bis[2-(2-methoxyethoxycarbonyl)ethyl]amine,N-methyl-bis(2-acetoxyethyl)amine, N-ethyl-bis(2-acetoxyethyl)amine,N-methyl-bis(2-pivaloyloxyethyl)amine,N-ethyl-bis[2-(methoxycarbonyloxy)ethyl]amine,N-ethyl-bis[2-(tert-butoxycarbonyloxy)ethyl]amine,tris(methoxycarbonylmethyl)amine, tri(ethoxycarbonylmethyl)amine,N-butyl-bis(methoxycarbonylmethyl)amine,N-hexyl-bis(methoxycarbonylmethyl)amine, andβ-(diethylamino)-δ-valerolactone.

Illustrative examples of the basic compounds include1-[2-(methoxymethoxy)ethyl]pyrrolidine,1-[2-(methoxymethoxy)ethyl]piperidine,4-[2-(methoxymethoxy)ethyl]morpholine,1-[2-(methoxymethoxy)ethyl]imidazole,1-[2-(methoxymethoxy)ethyl]benzimidazole,1-[2-(methoxymethoxy)ethyl]-2-phenylbenzimidazole,1-[2-[(2-methoxyethoxy)methoxy]ethyl]pyrrolidine,1-[2-[(2-methoxyethoxy)methoxy]ethyl]piperidine,4-[2-[(2-methoxyethoxy)methoxy]ethyl]morpholine,1-[2-[(2-methoxyethoxy)methoxy]ethyl]imidazole,1-[2-[(2-methoxyethoxy)methoxy]ethyl]benzimidazole,1-[2-[(2-methoxyethoxy)methoxy]ethyl]-2-phenylbenzimidazole,1-[2-[2-(2-methoxyethoxy)ethoxy]ethyl]pyrrolidine,1-[2-[2-(2-methoxyethoxy)ethoxy]ethyl]piperidine,4-[2-[2-(2-methoxyethoxy)ethoxy]ethyl]morpholine,1-[2-[2-(2-methoxyethoxy)ethoxy]ethyl]imidazole,1-[2-[2-(2-methoxyethoxy)ethoxy]ethyl]benzimidazole,1-[2-[2-(2-methoxyethoxy)ethoxy]ethyl]-2-phenylbenzimidazole,1-[2-[2-(2-butoxyethoxy)ethoxy]ethyl]pyrrolidine,1-[2-[2-(2-butoxyethoxy)ethoxy]ethyl]piperidine,4-[2-[2-(2-butoxyethoxy)ethoxy]ethyl]morpholine,1-[2-[2-(2-butoxyethoxy)ethoxy]ethyl]imidazole,1-[2-[2-(2-butoxyethoxy)ethoxy]ethyl]benzimidazole,1-[2-[2-(2-butoxyethoxy)ethoxy]ethyl]-2-phenylbenzimidazole,1-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethyl]pyrrolidine,1-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethyl]piperidine,4-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethyl]morpholine,1-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethyl]imidazole,1-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethyl]benzimidazole,1-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethyl]-2-phenyl-benzimidazole,4-[2-{2-[2-(2-butoxyethoxy)ethoxy]ethoxy}ethyl]morpholine,2-(1-pyrrolidinyl)ethyl acetate; 2-piperidinoethyl acetate,2-morpholinoethyl acetate, 2-(1-imidazolyl)ethyl acetate,2-(1-benzimidazolyl)ethyl acetate, 2-(2-phenyl-1-benzimidazolyl)ethylacetate, 2-methoxyethyl morpholinoacetate, 2-(1-pyrrolidinyl)ethyl2-methoxyacetate, 2-piperidinoethyl 2-methoxyacetate, 2-morpholinoethyl2-methoxyacetate, 2-(1-imidazolyl)ethyl 2-methoxyacetate,2-(1-benzimidazolyl)ethyl 2-methoxyacetate,2-(2-phenyl-1-benzimidazolyl)ethyl 2-methoxyacetate,2-(1-pyrrolidinyl)ethyl 2-(2-methoxyethoxy)acetate, 2-piperidinoethyl2-(2-methoxyethoxy)acetate, 2-morpholinoethyl2-(2-methoxyethoxy)acetate, 2-(1-imidazolyl)ethyl2-(2-methoxyethoxy)acetate, 2-(1-benzimidazolyl)ethyl2-(2-methoxyethoxy)acetate, 2-(2-phenyl-1-benzimidazolyl)ethyl2-(2-methoxyethoxy)acetate, 2-(1-pyrrolidinyl)ethyl2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-piperidinoethyl2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-morpholinoethyl2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-(1-imidazolyl)ethyl2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-(1-benzimidazolyl)ethyl2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-(2-phenyl-1-benzimidazolyl)ethyl2-[2-(2-methoxyethoxy)-ethoxy]acetate, 2-morpholinoethyl butyrate,2-morpholinoethyl hexanoate, 2-morpholinoethyl octanoate,2-morpholinoethyl decanoate, 2-morpholinoethyl laurate,2-morpholinoethyl myristate, 2-morpholinoethyl palmitate,2-morpholinoethyl stearate, 2-morpholinoethyl behenate,2-morpholinoethyl cholate, 2-morpholinoethyl tris(O-acetyl)cholate,2-morpholinoethyl tris(O-formyl)cholate, 2-morpholinoethyldehydrocholate, 2-morpholinoethyl cyclopentanecarboxylate,2-morpholinoethyl cyclohexanecarboxylate, 2-(1-pyrrolidinyl)ethyl7-oxanorbornane-2-carboxylate, 2-piperidinoethyl7-oxanorbornane-2-carboxylate, 2-morpholinoethyl7-oxanorbornane-2-carboxylate, 2-(1-imidazolyl)ethyl7-oxanorbornane-2-carboxylate, 2-(1-benzimidazolyl)ethyl7-oxanorbornane-2-carboxylate, 2-(2-phenyl-1-benzimidazolyl)ethyl7-oxanorbornane-2-carboxylate, 2-morpholinoethyl adamantanecarboxylate,2-(1-pyrrolidinyl)ethyl formate, 2-piperidinoethyl propionate,2-morpholinoethyl acetoxyacetate, 2-(1-pyrrolidinyl)ethylmethoxyacetate, 2-(1-pyrrolidinyl)ethyl benzoate, 2-piperidinoethylbenzoate, 2-morpholinoethyl benzoate, 2-(1-imidazolyl)ethyl benzoate,2-(1-benzimidazolyl)ethyl benzoate, 2-(2-phenyl-1-benzimidazolyl)ethylbenzoate, 2-(1-pyrrolidinyl)ethyl 4-methoxybenzoate, 2-piperidinoethyl4-methoxybenzoate, 2-morpholinoethyl 4-methoxybenzoate,2-(1-imidazolyl)ethyl 4-methoxybenzoate, 2-(1-benzimidazolyl)ethyl4-methoxybenzoate, 2-(2-phenyl-1-benzimidazolyl)ethyl 4-methoxybenzoate,2-(1-pyrrolidinyl)ethyl 4-phenylbenzoate, 2-piperidinoethyl4-phenylbenzoate, 2-morpholinoethyl 4-phenylbenzoate,2-(1-imidazolyl)ethyl 4-phenylbenzoate, 2-(1-benzimidazolyl)ethyl4-phenylbenzoate, 2-(2-phenyl-1-benzimidazolyl)ethyl 4-phenylbenzoate,2-(1-pyrrolidinyl)ethyl 1-naphthalenecarboxylate, 2-piperidinoethyl1-naphthalenecarboxylate, 2-morpholinoethyl 1-naphthalenecarboxylate,2-(1-imidazolyl)ethyl 1-naphthalenecarboxylate,2-(1-benzimidazolyl)ethyl 1-naphthalenecarboxylate,2-(2-phenyl-1-benzimidazolyl)ethyl 1-naphthalenecarboxylate,2-(1-pyrrolidinyl)ethyl 2-naphthalenecarboxylate, 2-piperidinoethyl2-naphthalenecarboxylate, 2-morpholinoethyl 2-naphthalenecarboxylate,2-(1-imidazolyl)ethyl 2-naphthalenecarboxylate,2-(1-benzimidazolyl)ethyl 2-naphthalenecarboxylate,2-(2-phenyl-1-benzimidazolyl)ethyl 2-naphthalenecarboxylate,4-[2-(methoxycarbonyloxy)ethyl]morpholine,1-[2-(t-butoxycarbonyloxy)ethyl]piperidine,4-[2-(2-methoxyethoxycarbonyloxy)ethyl]morpholine, methyl3-(1-pyrrolidinyl)propionate, methyl 3-piperidinopropionate, methyl3-morpholinopropionate, methyl 3-(thiomorpholino)propionate, methyl2-methyl-3-(1-pyrrolidinyl)propionate, ethyl 3-morpholinopropionate,methoxycarbonylmethyl 3-piperidinopropionate, 2-hydroxyethyl3-(1-pyrrolidinyl)propionate, 2-acetoxyethyl 3-morpholinopropionate,2-oxotetrahydrofuran-3-yl 3-(1-pyrrolidinyl)propionate,tetrahydrofurfuryl 3-morpholinopropionate, glycidyl3-piperidinopropionate, 2-methoxyethyl 3-morpholinopropionate,2-(2-methoxyethoxy)ethyl 3-(1-pyrrolidinyl)propionate, butyl3-morpholinopropionate, cyclohexyl 3-piperidinopropionate,α-(1-pyrrolidinyl)methyl-γ-butyrolactone, β-piperidino-γ-butyrolactone,β-morpholino-δ-valerolactone, methyl 1-pyrrolidinylacetate, methylpiperidinoacetate, methyl morpholinoacetate, methylthiomorpholinoacetate, ethyl 1-pyrrolidinylacetate, etc.

The dissolution regulator or inhibitor (F) which can be added to theresist composition is a compound having on the molecule at least twophenolic hydroxyl groups which are protected with an acid labile group,or a compound having on the molecule at least one carboxyl group whichis protected with an acid labile group. Exemplary regulators aredescribed in JP-A 2008-122932, paragraphs [0155] to [0178].

Optionally, the resist composition may further comprise (G) a surfactantwhich is commonly used for facilitating the coating operation. Exemplarysurfactants are described in JP-A 2008-111103, paragraph [0166].

Optionally, the resist composition may further comprise (H) an acetylenealcohol derivative. Exemplary compounds are described in JP-A2008-122932, paragraphs to [0181].

Pattern Forming Process

It is now described how to form a pattern using the resist compositionof the invention. A pattern may be formed from the resist composition ofthe invention using any well-known lithography process. The preferredmethod includes at least the steps of forming a photoresist coating on asubstrate, exposing it to high-energy radiation, and developing it witha developer.

The resist composition is applied onto a substrate, typically a siliconwafer by a suitable coating technique such as spin coating. The coatingis prebaked on a hot plate at a temperature of 60 to 150° C. for 1 to 10minutes, preferably 80 to 140° C. for 1 to 5 minutes, to form aphotoresist film of 0.1 to 2.0 μm thick. It is noted in conjunction withspin coating that if the resist composition is coated onto the surfaceof a substrate which has been wetted with the resist solvent or asolution miscible with the resist solvent, then the amount of the resistcomposition dispensed can be reduced (see JP-A 9-246173).

A patterning mask having the desired pattern is then placed over thephotoresist film, and the film exposed through the mask to an electronbeam or to high-energy radiation such as deep-UV, excimer laser or x-rayin a dose of 1 to 200 mJ/cm², and preferably 10 to 100 mJ/cm². Thehigh-energy radiation used herein preferably has a wavelength in therange of 180 to 250 nm.

Light exposure may be dry exposure in air or nitrogen atmosphere, EB orEUV exposure in vacuum, or immersion lithography of providing a liquid,typically water between the photoresist film and the projection lens.

The immersion lithography involves prebaking a resist film and exposingthe resist film to light through a projection lens, with pure water orsimilar liquid interposed between the resist film and the projectionlens. Since this allows projection lenses to be designed to a NA of 1.0or higher, formation of finer patterns is possible. The immersionlithography is important for the ArF lithography to survive to the 45-nmnode. The liquid used herein may be a liquid with a refractive index ofat least 1 which is highly transparent at the exposure wavelength,typically pure water or alkane.

The photoresist film formed from the resist composition of the inventionhas such barrier properties to water that it may inhibit resistcomponents from being leached out in water and as a consequence,eliminate a need for a protective coating in immersion lithography andreduce the cost associated with protective coating formation or thelike. The photoresist film has so high a receding contact angle withwater that few liquid droplets may be left on the surface of thephotoresist film after immersion lithography scanning, minimizingpattern formation failures induced by liquid droplets left on the filmsurface.

In another version of immersion lithography, a protective coating may beformed on top of the resist film. The resist protective coating used inthe immersion lithography may be formed from a coating solution, forexample, a topcoat solution of a polymer having acidic units such as1,1,1,3,3,3-hexafluoro-2-propanol, carboxyl or sulfo groups which isinsoluble in water and soluble in an alkaline developer liquid, in asolvent selected from alcohols of at least 4 carbon atoms, ethers of 8to 12 carbon atoms, and mixtures thereof. The resist protective coatingis not limited thereto.

The resist protective coating may be formed by spin coating a topcoatsolution onto a prebaked photoresist film, and prebaking on a hot plateat 50 to 150° C. for 1 to 10 minutes, preferably at 70 to 140° C. for 1to 5 minutes. Preferably the protective coating has a thickness in therange of 10 to 500 nm. As in the case of resist compositions, the amountof the protective coating material dispensed in forming a protectivecoating by spin coating may be reduced by previously wetting the resistfilm surface with a suitable solvent and applying the protective coatingmaterial thereto.

After exposure to high-energy radiation through a photomask, the resistfilm is post-exposure baked (PEB) on a hot plate at 60 to 150° C. for 1to 5 minutes, and preferably at 80 to 140° C. for 1 to 3 minutes.

Where a resist protective coating is used, sometimes water is left onthe protective coating prior to PEB. If PEB is performed in the presenceof residual water, water can penetrate through the protective coating tosuck up the acid in the resist during PEB, impeding pattern formation.To fully remove the water on the protective coating prior to PEB, thewater on the protective coating should be dried or recovered by suitablemeans, for example, spin drying, purging the protective coating surfacewith dry air or nitrogen, or optimizing the shape of a water recoverynozzle on the relevant stage or a water recovery process.

After exposure, development is carried out using as the developer anaqueous alkaline solution, such as a 0.1 to 5 wt %, preferably 2 to 3 wt%, aqueous solution of tetramethylammonium hydroxide (TMAH), this beingdone by a conventional method such as dip, puddle, or spray developmentfor a period of 10 to 300 seconds, and preferably 0.5 to 2 minutes. Atypical developer is a 2.38 wt % TMAH aqueous solution. These stepsresult in the formation of the desired pattern on the substrate.

Where polymer P1 is used as an additive to a resist material for usewith mask blanks, a resist solution is prepared by adding polymer P1 toany one of the aforementioned base resins and dissolving them in anorganic solvent. The resist solution is coated on a mask blank substrateof SiO₂, Cr, CrO, CrN, MoSi or the like. By further forming a SOG filmand an organic undercoat film between the photoresist and the blanksubstrate, there is provided a three-layer structure which is alsoacceptable herein.

As the base resin of the resist composition for use with mask blanks,novolac resins and hydroxystyrene are often used , Those resins in whichalkali soluble hydroxyl groups are substituted by acid labile groups areused for positive resists while these resins in combination withcrosslinking agents are used for negative resists. Base polymers whichcan be used herein include copolymers of hydroxystyrene with one or moreof (meth)acrylic derivatives, styrene, vinyl naphthalene, vinylanthracene, vinyl pyrene, hydroxyvinyl naphthalene, hydroxyvinylanthracene, indene, hydroxyindene, acenaphthylene, and norbornadiene.

Once the resist coating is formed, the structure is exposed to EB invacuum using an EB image-writing system. The exposure is followed bypost-exposure baking (PEB) and development in an alkaline developer for10 to 300 seconds, thereby forming a pattern.

Example

Examples are given below by way of illustration and not by way oflimitation. The abbreviations Mw and Mn are weight and number averagemolecular weights, respectively, as measured by GPC using polystyrenestandards, and Mw/Mn is a polydispersity index. Me stands for methyl, Etfor ethyl, and PGMEA for propylene glycol monomethyl ether acetate.

[Monomer Synthesis]

Fluorinated monomers within the scope of the invention were synthesized.

Example 1

Synthesis of Monomer 1

While a mixture of 50.0 g of Hemiacetal-1, 40.8 g of pyridine, and 100 gof acetonitrile was stirred under ice cooling in a nitrogen atmosphere,22.0 g of isobutyric acid chloride was added dropwise over 30 minutes.After 30 minutes, the reaction solution was diluted by adding 100 g ofhexane, and 400 g of water was then added to the reaction solution,which was stirred for 30 minutes to quench the reaction and decomposethe excess reactants. After ordinary aqueous work-up, the reactionproduct was purified by vacuum distillation, obtaining 60.8 g of thetarget compound (yield 98%). Colorless liquid, boiling point 63-67°C./13 Pa. On NMR analysis, it was a mixture of diastereomers in a molarratio 67:33.

IR (thin film): ν=2981, 2940, 2883, 1774, 1727, 1639, 1471, 1452, 1388,1336, 1303, 1282, 1218, 1155, 1112, 1081, 1039, 1004, 939, 927 cm⁻¹

¹H-NMR (300 MHz in DMSO-d₆) of mixture of 67:33 (mole) diastereomers:δ=1.11 (0.99H, d, J=6.9 Hz), 1.12 (0.99H, d, J=7.1 Hz), 1.14 (4.02H, d,J=6.9 Hz), 1.66-1.70 (3H, m), 1.85-1.90 (3H, m), 2.70 (0.33H, qq, J=7.1,6.9 Hz), 2.74 (0.67H, sep, J=6.9 Hz), 4.65 (0.67H, br.d, J=11.1 Hz),4.68 (0.33H, dd, J=9.8, 1.5 Hz), 4.79 (0.33H, br.d, J=9.8 Hz), 4.85(0.67H, dd, J=11.1, 2.7 Hz), 5.80 (0.67H, m), 5.82 (0.33H, m), 6.08(0.67H, m), 6.09 (0.33H, m) ppm

¹⁹F-NMR (283 MHz in DMSO-d₆) of mixture of 67:33 (mole) diastereomers:δ=−124.32 (0.67F, dq, J=250, 17 Hz), −119.75 (0.33F, dqd, J=246, 17.4Hz), −110.80 (0.33F, d, J=246 Hz), −109.49 (0.67F, d, J=250 Hz), −80.19(0.67F, d, J=17 Hz), −79.92 (0.33F, d, J=17 Hz) ppm

Example 2

Synthesis of Monomer 2

A mixture of 32.0 g of Hemiacetal-2, 28.4 g of methyl iodide, 27.8 g ofsilver(I) oxide, and 150 g of ethyl acetate was stirred at 40° C. for 24hours. After the insoluble was filtered off, the reaction mixture wasvacuum concentrated and purified by silica gel column chromatography,obtaining 27.1 g of the target compound (yield 81%).

Example 3

Synthesis of Monomer 3

To a mixture of 40.8 g of Hemiacetal-3, 15.2 g of triethylamine, 1.5 gof sodium iodide, and 200 g of acetonitrile was added 10.5 g ofchloromethyl methyl ether. The mixture was stirred at 50° C. for 16hours. After ordinary aqueous work-up, the reaction product was purifiedby silica gel column chromatography, obtaining 43.0 g of the targetcompound (yield 95%).

Example 4

Synthesis of Monomer 4

Monomer 4 was synthesized by the same procedure as in Example 1 asidefrom using Hemiacetal-4 instead of Hemiacetal-1, and2,6-norbornanecarbolactone-3-carbonyl chloride instead of isobutyricacid chloride.

Example 5

Synthesis of Monomer 5

Monomer 5 was synthesized by the same procedure as in Example 3 asidefrom using Hemiacetal-5 instead of Hemiacetal-3, and2-chlorotetrahydropyran instead of chloromethyl methyl ether.

Example 6

Synthesis of Monomer 6

Monomer 6 was synthesized by the same procedure as in Example 2 asidefrom using Hemiacetal-6 instead of Hemiacetal-2, and isobutyl iodideinstead of methyl iodide.

Example 7

Synthesis of Monomer 7

Monomer 7 was synthesized by the same procedure as in Example 3 asidefrom using Hemiacetal-7 instead of Hemiacetal-3, and chloromethylmenthyl ether instead of chloromethyl methyl ether.

Example 8

Synthesis of Monomer 8

Monomer 8 was synthesized by the same procedure as in Example 3 asidefrom using Hemiacetal-8 instead of Hemiacetal-3, and 1-chloroethyl ethylether instead of chloromethyl methyl ether.

Example 9

Synthesis of Monomer 9

Monomer 9 was synthesized by the same procedure as in Example 2 asidefrom using Hemiacetal-9 instead of Hemiacetal-2, and1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluoro-1-iodooctane instead of methyliodide.

Example 10

Synthesis of Monomer 10

Monomer 10 was synthesized by the same procedure as in Example 1 asidefrom using acetic anhydride instead of isobutyric acid chloride.

Example 11

Synthesis of Monomer 11

Monomer 11 was synthesized by the same procedure as in Example 1 asidefrom using isovaleric acid chloride instead of isobutyric acid chloride.

Colorless liquid, boiling point 70° C./13 Pa

IR (thin film): ν=2966, 2935, 2877, 1779, 1727, 1639, 1469, 1452, 1386,1371, 1336, 1301, 1282, 1216, 1155, 1110, 1087, 1039, 1004, 946, 927cm⁻¹

¹H-NMR (600 MHz in DMSO-d₆) of mixture of 65:35 (mole) diastereomers:δ=0.89 (1.05H, d, J=6.4 Hz), 0.90 (1.05H, d, J=6.4 Hz), 0.92 (1.95H, d,J=6.4 Hz), 0.92 (1.95H, d, J=6.4 Hz), 1.66 (1.05H, br.d, J=3.7 Hz), 1.68(1.95H, br.d, J=3.2 Hz), 1.86 (1.95H, m), 1.87 (1.05H, m), 1.90-2.05(1H, m), 2.31 (0.35H, dd, J=15.6, 7.3 Hz), 2.36 (0.65H, dd, J=15.5, 6.8Hz), 2.37 (0.35H, dd, J=15.6, 6.4 Hz), 2.40 (0.65H, dd, J=15.5, 6.9 Hz),4.63 (0.65H, br.d, J=11.0 Hz), 4.66 (0.35H, dd, J=10.1, 1.0 Hz), 4.77(0.35H, br.d, J=10.1 Hz), 4.83 (0.65H, dd, J=11.0, 2.3 Hz), 5.78 (0.65H,m), 5.81 (0.35H, m), 6.06 (0.65H, m), 6.08 (0.35H, m) ppm

¹⁹F-NMR (565 MHz in DMSO-d₆) of mixture of 65:35 (mole) diastereomers:δ=−124.06 (0.65F, dq, J=249, 16 Hz), −119.57 (0.35F, dqd, J=246, 17.3Hz), −110.46 (0.35F, d, J=246 Hz), −108.98 (0.65F, d, J=249 Hz), −79.90(0.65F, d, J=16 Hz), −79.57 (0.35F, d, J=18 Hz) ppm

Example 12

Synthesis of Monomer 12

Monomer 12 was synthesized by the same procedure as in Example 1 asidefrom using trifluoroacetic anhydride instead of isobutyric acidchloride.

Colorless liquid, boiling point 74° C./800 Pa

IR (thin film): ν=2989, 2937, 1814, 1731, 1639, 1454, 1405, 1388, 1340,1301, 1282, 1228, 1180, 1153, 1101, 1012, 950, 919, 842 cm⁻¹

¹H-NMR (300 MHz in DMSO-d₆) of mixture of 60:40 (mole) diastereomers:δ=1.71 (1.2H, br.d, J=3.8 Hz), 1.73 (1.8H, br.d, J=3.3 Hz), 1.88 (1.2H,m), 1.89 (1.8H, m), 4.80 (0.6H, br.d, J=11.1 Hz), 4.87 (0.4H, dd,J=10.6, 1.2 Hz), 5.01 (0.4H, br.d, J=10.6 Hz), 5.03 (0.6H, dd, J=11.1,2.5 Hz), 5.81 (0.4H, m), 5.83 (0.4H, m), 6.06 (0.4H, m), 6.10 (0.4H, m)ppm

¹⁹F-NMR (283 MHz in DMSO-d₆) of mixture of 60:40 (mole) diastereomers:δ=−124.81 (0.6F, dq, J=248, 16 Hz), −120.54 (0.4F, dqd, 3=246, 17.3 Hz),−117.96 (0.4F, d, J=246 Hz), −113.14 (0.6F, d, J=248 Hz), −79.29 (0.6F,d, J=16 Hz), −78.74 (0.4F, d, J=16 Hz), −75.95 (0.4F, s), −75.92 (0.6F,s) ppm

Example 13

Synthesis of Monomer 13

Monomer 13 was synthesized by the same procedure as in Example 3 asidefrom using Hemiacetal-1 instead of Hemiacetal-3, and1-chloro-1-methoxy-2-methylpropane instead of chloromethyl methyl ether.

Colorless liquid, boiling point 70° C./27 Pa

IR (thin film): ν=2969, 2881, 2848, 1727, 1639, 1473, 1452, 1388, 1367,1328, 1303, 1284, 1207, 1159, 1103, 1066, 1010, 970, 946 cm⁻¹

¹H-NMR (600 MHz in DMSO-d₆) of mixture of 33:32:19:16 (mole) fourdiastereomers: δ=0.80-0.90 (6H, m), 1.61-1.71 (3H, m), 1.84-1.95 (4H,m), 3.20 (0.16H, s), 3.26 (0.19H, s), 3.30 (0.33H, s), 3.34 (0.32H, s),4.35-4.80 (2H, m), 5.72-5.82 (1H, m), 6.05-6.10 (1H, m) ppm

¹⁹F-NMR (565 MHz in DMSO-d₆) of mixture of 33:32:19:16 (mole)diastereomers: δ=−124.63 (0.33F, dq, J=243, 19 Hz), −124.30 (0.32F, dq,J=236, 18 Hz), −121.63 (0.32F, d, J=236 Hz), −121.49 (0.16F, d, J=241Hz), −120.52 (0.16F, dq, J=241, 17 Hz), −119.38 (0.19F, dq, J=245, 21Hz), −116.83 (0.19F, d, J=24.5 Hz), −114.83 (0.33F, d, J=243 Hz), −79.00(0.19F, d, J=21 Hz), −78.76 (0.33F, d, J=20 Hz), −78.29 (0.16F, d, J=18Hz), −78.23 (0.32F, d, J=20 Hz) ppm

[Polymer Synthesis]

Polymerizable monomers (Monomers 14 to 29) and an amine (Base 1) used inpolymer synthesis are identified below by their structural formulae.

Polymer Synthesis Example 1

Copolymerization of Monomers 14 and 19 (20/80)

In a nitrogen atmosphere, a flask was charged with 23.41 g of Monomer14, 77.11 g of Monomer 19, 3.75 g of 2,2′-azobis(isobutyric acid)dimethyl, and 100.1 g of methyl ethyl ketone to form a monomer solutionat a temperature of 20-25° C. In a nitrogen atmosphere, another flaskwas charged with 50.1 g of methyl ethyl ketone, which was heated at 80°C. with stirring. The monomer solution was added dropwise thereto over 4hours. After the completion of dropwise addition, the polymerizationsolution was stirred for a further 2 hours while maintaining thetemperature of 80° C. At the end of maturing, the solution was cooled toroom temperature. To the flask 200 g of toluene was admitted. Using anevaporator, the reaction mixture was concentrated until the total weightreached 250 g. The concentrate was added dropwise to 1,500 g of hexane.The copolymer thus precipitated was separated and washed with 600 g ofhexane, obtaining a white solid. The solid was vacuum dried at 50° C.for 20 hours, yielding 69.3 g of the target polymer, designated Polymer2. On ¹H-NMR analysis of resin composition, the copolymer consisted ofMonomers 14 and 19 in a ratio of 19/81 mol %.

Polymer Synthesis Examples 2 to 19

As in Polymer Synthesis Example 1, Polymers 1 to 19 were synthesizedusing the polymerizable monomers (Monomers 14 to 29) in accordance withthe formulation shown in Tables 1 to 5.

TABLE 1 Monomer Yield 14 18 19 20 21 (%) Mw Mw/Mn Polymer 1 20 80 68.27,400 1.4 Polymer 2 20 80 69.3 7,800 1.4 Polymer 3 20 80 70.2 7,500 1.4Polymer 4 20 80 69.8 7,400 1.4

TABLE 2 Monomer Yield 15 16 17 19 (%) Mw Mw/Mn Polymer 5 20 80 69.27,300 1.4 Polymer 6 20 80 71.2 7,100 1.4 Polymer 7 20 80 70.5 7,100 1.4

TABLE 3 Monomer Yield 14 18 19 20 21 (%) Mw Mw/Mn Polymer 8 40 60 71.27,300 1.4 Polymer 9 40 60 72.4 7,700 1.4 Polymer 10 40 60 71.6 7,600 1.4Polymer 11 40 60 69.4 7,500 1.4

TABLE 4 Monomer Yield 15 16 17 19 (%) Mw Mw/Mn Polymer 12 40 60 72.47,200 1.4 Polymer 13 40 60 71.1 7,500 1.4 Polymer 14 40 60 70.7 7,4001.4

TABLE 5 Monomer Yield 14 19 22 23 24 25 26 (%) Mw Mw/Mn Polymer 15 20 7010 68.9 7,400 1.4 Polymer 16 20 70 10 70.5 7.500 1.4 Polymer 17 20 70 1071.4 7,400 1.4 Polymer 18 20 70 10 72.1 7,300 1.4 Polymer 19 20 70 1071.8 7,600 1.4

Polymer Synthesis Example 20

Copolymerization of Monomers 19 and 27 (90/10) in the Presence of Base 1

In a nitrogen atmosphere, a flask was charged with 96.46 g of Monomer19, 4.03 g of Monomer 27, 1.87 g of Base 1, 4.18 g of2,2′-azobis(isobutyric acid) dimethyl, and 155.56 g of isopropyl alcoholto form a monomer solution at a temperature of 20-25° C. In a nitrogenatmosphere, another flask was charged with 77.78 g of isopropyl alcohol,which was heated at 80° C. with stirring. The monomer solution was addeddropwise thereto over 4 hours. After the completion of dropwiseaddition, the polymerization solution was stirred for a further 2 hourswhile maintaining the temperature of 80° C. At the end of maturing, thesolution was cooled to room temperature. After 300 g of 2-propanol wasadded, the polymerization solution was washed three times with 300 g ofultrapure water. The organic layer extracted was concentrated on anevaporator until the total weight reached 200 g. The concentrate wascrystallized in 1,500 g of hexane. The copolymer thus precipitated wasseparated and washed with 600 g of hexane, obtaining a white solid. Thesolid was vacuum dried at 50° C. for 20 hours, yielding 79.8 g of thetarget polymer, designated Polymer 20. On ¹H-NMR analysis of resincomposition, the copolymer consisted of Monomer 19, Monomer 27 and Base1 salt in a ratio of 89/9/2 mol % as shown below.

Polymer Synthesis Example 21

Copolymerization of Monomers 19 and 28 (90/10) in the Presence of Base 1

By the same procedure as in the synthesis of Polymer 20, aside fromusing Monomer 19, Monomer 28 and Base 1, 75.3 g of the target polymer(Polymer 21) was synthesized. On ¹H-NMR analysis of resin composition,the copolymer consisted of Monomer 19, Monomer 28 and Base 1 salt in aratio of 90/8/2 mol % as shown below.

Polymer Synthesis Example 22

Copolymerization of Monomers 19 and 29 (90/10)

By the same procedure as in the synthesis of Polymer 20, aside fromusing Monomers 19 and 29, 81.5 g of the target polymer (Polymer 22) wassynthesized. On ¹H-NMR analysis of resin composition, the copolymerconsisted of Monomers 19 and 29 in a ratio of 90/10 mol % as shownbelow.

Comparative Polymer Synthesis Example 1

Synthesis of Homopolymer of Monomer 19

In a nitrogen atmosphere, a flask was charged with 100.0 g of Monomer19, 3.91 g of 2,2′-azobis(isobutyric acid) dimethyl, and 100.0 g ofisopropyl alcohol to form a monomer solution at a temperature of 20-25°C. In a nitrogen atmosphere, another flask was charged with 50.0 g ofisopropyl alcohol, which was heated at 80° C. with stirring. The monomersolution was added dropwise thereto over 4 hours. After the completionof dropwise addition, the polymerization solution was stirred for afurther 3 hours while maintaining the temperature of 80° C. At the endof maturing, the solution was cooled to room temperature. Thepolymerization solution was added dropwise to 2,000 g of water. Thepolymer thus precipitated was filtered and washed four times with 600 gof a 9/1 hexane/isopropyl ether mixture, obtaining a white solid. Thesolid was vacuum dried at 50° C. for 20 hours, yielding 92.8 g of thetarget polymer, designated Comparative Polymer 1. On GPC analysis, thepolymer had Mw of 7,800 and Mw/Mn of 1.6.

[Evaluation of Protective Coating]

Resist protective topcoat solutions TC-1 to 27 and Comparative-TC-1 to 2were prepared by dissolving 1.0 g of each of Inventive Polymers 1 to 22and Comparative Polymer 1 in a solvent mixture of 23 g of diisopentylether and 2 g of 2-methyl-1-butanol in accordance with the formulationof Table 6 and filtering through a polypropylene filter with a pore sizeof 0.2 μm.

The resist protective topcoat solutions were spin coated onto siliconsubstrates and baked at 100° C. for 60 seconds to form protective filmsTC-1 to 27 and Comparative-TC-1 to 2 of 50 nm thick. The wafers coatedwith protective films were tested for the following properties: (1) arefractive index at wavelength 193 nm using a spectroscopic ellipsometerof J. A. Woollam Co., (2) a film thickness change after rinsing withpure water for 5 minutes, (3) a film thickness change after developmentwith 2.38 wt % tetramethylammonium hydroxide (TMAH) aqueous solution,and (4) a sliding angle and a receding contact angle using aninclination contact angle meter Drop Master 500 (Kyowa Interface ScienceCo., Ltd.). The results are shown in Table 6.

TABLE 6 Film thickness Film change thickness after change RecedingResist Polymers in Refractive water after Sliding contact protectiveprotective topcoat index rinsing development angle angle topcoat (mixratio) @193 nm (nm) (nm) (°) (°) TC-1 Polymer 1 (100) 1.54 0 0 13 67TC-2 Polymer 2 (100) 1.54 0 0 11 76 TC-3 Polymer 3 (100) 1.54 0 0 11 75TC-4 Polymer 4 (100) 1.54 0 0 10 76 TC-5 Polymer 5 (100) 1.54 0 0 11 74TC-6 Polymer 6 (100) 1.54 0 0 10 78 TC-7 Polymer 7 (100) 1.54 0 0 12 73TC-8 Polymer 8 (100) 1.54 0 0 13 70 TC-9 Polymer 9 (100) 1.54 0 0 10 79TC-10 Polymer 10 (100) 1.54 0 0 10 79 TC-11 Polymer 11 (100) 1.54 0 0 980 TC-12 Polymer 12 (100) 1.54 0 0 10 78 TC-13 Polymer 13 (100) 1.54 0 010 80 TC-14 Polymer 14 (100) 1.54 0 0 10 77 TC-15 Polymer 15 (100) 1.540 0 10 76 TC-16 Polymer 16 (100) 1.54 0 0 10 77 TC-17 Polymer 17 (100)1.54 0 0 12 73 TC-18 Polymer 18 (100) 1.54 0 0 12 74 TC-19 Polymer 19(100) 1.54 0 0 11 75 TC-20 Polymer 8 (75) 1.54 0 0 12 69 Polymer 20 (25)TC-21 Polymer 9 (75) 1.54 0 0 9 78 Polymer 20 (25) TC-22 Polymer 10 (75)1.54 0 0 9 78 Polymer 20 (25) TC-23 Polymer 11 (75) 1.54 0 0 9 79Polymer 20 (25) TC-24 Polymer 12 (75) 1.54 0 0 9 77 Polymer 20 (25)TC-25 Polymer 14 (75) 1.54 0 0 9 77 Polymer 20 (25) TC-26 Polymer 9 (75)1.54 0 0 9 80 Polymer 21 (25) TC-27 Polymer 9 (75) 1.54 0 0 9 81 Polymer22 (25) Comparative Comparative Polymer 1 (100) 1.54 0 0 15 69 TC-1Comparative Comparative Polymer 1 (75) 1.54 0 0 15 68 TC-2 Polymer 20(25)

As seen from Table 6, the inventive polymers P1 have a greater recedingcontact angle than the comparative polymer. The value of recedingcontact angle differs little between a P1/P2 polymer blend and polymerP1 alone, demonstrating effective layer separation between polymers P1and P2, that is, a layer of polymer P1 is disposed on top of a layer ofpolymer P2. In general, a smaller sliding angle indicates an easier flowof water on the protective coating; and a larger receding contact angleindicates that fewer liquid droplets are left during high-speed scanexposure. It is seen from Table 6 that the protective topcoats TC-1 to27 within the scope of the invention are improved in sliding angle andring contact angle over Comparative TC-1 to 2.

[Evaluation of Resist]

A resist solution was prepared by dissolving 5 g of Resist Polymer, 0.5g of a photoacid generator PAG1, and 0.1 g of Quencher 1 (all shownbelow) in 100 g of PGMEA and filtering through a polypropylene filterhaving a pore size of 0.2 μm.

An antireflective coating ARC-29A (Nissan Chemical Co., Ltd.) wasdeposited on a silicon substrate to a thickness of 87 nm. The resistsolution was applied onto the ARC and baked at 105° C. for 60 seconds toform a resist film of 120 nm thick. The protective topcoat solution(prepared above) was applied onto the resist film and baked at 100° C.for 60 seconds. In order to simulate immersion lithography, lightexposure was preceded by rinsing of the coating with pure water for 5minutes. The structure was exposed by means of an ArF scanner modelS307E (Nikon Corp., NA 0.85, a 0.93/0.62, 20° dipole illumination, 6%halftone phase shift mask), rinsed for 5 minutes while splashing purewater, post-exposure baked (PEB) at 100° C. for 60 seconds, anddeveloped with a 2.38 wt % TMAH aqueous solution for 60 seconds. As acomparative run, a similar process including light exposure, waterrinsing, PEB and development was carried out in the absence of theprotective coating. The wafers were sectioned for comparing the profileof 65-nm line-and-space pattern and sensitivity. Further, 0.5 μl ofwater droplet was dropped on the resist film after development, and acontact angle at the interface between the resist and water droplet wasmeasured. The results are shown in Table 7.

TABLE 7 Contact angle with water after Resist protective Sensitivity65-nm development topcoat (mJ/cm²) pattern profile (°) TC-20 30rectangular 60 TC-21 29 rectangular 59 TC-22 29 rectangular 60 TC-23 30rectangular 61 TC-24 30 rectangular 61 TC-25 30 rectangular 60 TC-26 30rectangular 60 TC-27 30 rectangular 60 Comparative TC-1 28 rounded top68 Comparative TC-2 29 rounded top 70 no protective film 30 T-top 62

When water rinsing was carried out after exposure in the absence of aprotective topcoat, the resist pattern had a

T-top profile. This is presumably because the acid generated wasdissolved in water. In the presence of a protective topcoat according tothe invention which had a large receding contact angle, the resist filmhad a reduced contact angle after development and produced a resistpattern of rectangular profile after development.

A protective topcoat of polymer P1 alone has a large receding contactangle, but provides a large contact angle with water after development.In contrast, a film of polymer P2 having a sulfonic acid amine salt isinferior in water repellency and water sliding property, but provides asmall contact angle with water after development and a resist pattern ofrectangular profile. A blend of polymer P1 with polymer P2 forms aprotective topcoat which has a large receding contact angle and providesa small contact angle with water after development.

In a further run, some resist protective topcoat solutions (TC-21 andComparative TC-2) used in the exposure experiment were precisionfiltered through a high-density polyethylene filter with a pore size of0.02 μm. An antireflective coating ARC-29A (Nissan Chemical Co., Ltd.)of 87 nm thick was deposited on a 8-inch silicon substrate. The resistsolution was applied onto the ARC and baked at 105° C. for 60 seconds toform a resist film of 120 nm thick. Each protective topcoat solution wascoated thereon and baked at 100° C. for 60 seconds. Using an ArF scannermodel S307E (Nikon Corp., NA 0.85, σ 0.93, Cr mask), the entire surfaceof the wafer was subjected to checkered-flag exposure includingalternate exposure of open-frame exposed and unexposed portions havingan area of 20 mm square. This was followed by post-exposure baking (PEB)and development with a 2.38 wt % TMAH aqueous solution for 60 seconds.

Using a flaw detector Win-Win 50-1200 (Tokyo Seimitsu Co., Ltd.), thenumber of defects in the unexposed portion of the checkered-flag wascounted at the pixel size of 0.125 μm. Those defects on the resistsurface in the unexposed portion are stain-like defects and classifiedas blob defects. The results are shown in Table 8. It is evident thatthe protective topcoat compositions comprising a blend of polymers P1and P2 produce a dramatically reduced number of defects, as comparedwith the comparative protective topcoat composition.

TABLE 8 Resist protective topcoat Number of defects TC-21 16 ComparativeTC-2 3,000

[EB Lithography]

In an EB image writing test, a positive resist material was prepared bydissolving 90 parts by weight of EB Polymer synthesized by radicalpolymerization, 10 parts by weight of PAG2, and 0.4 part by weight ofQuencher 2 (all shown below) in 700 parts by weight of PGMEA and 300parts by weight of ethyl lactate (EL) and filtering through a filterwith a pore size of 0.2 μm.

Using Clean Track Mark 5 (Tokyo Electron Ltd.), the positive resistmaterial was spin coated on a silicon substrate with a diameter of 6inches (150 mm) and prebaked on a hot plate at 110° C. for 60 seconds toform a resist film of 200 nm thick. A protective coating was coatedthereon. Using HL-800D (Hitachi, Ltd.) at a HV voltage of 50 keV,imagewise exposure was performed on the wafer in a vacuum chamber. Thewafer was then allowed to stand in the vacuum chamber for 20 hours,after which additional imagewise exposure was performed at a differentarea.

Using Clean Track Mark 5 (Tokyo Electron Ltd.), immediately after theimagewise exposure, the wafer was post-exposure baked (PEB) on a hotplate at 90° C. for 60 seconds and puddle developed in a 2.38 wt % TMAHaqueous solution for 30 seconds to form a positive pattern.

Using a measurement SEM S-7280 (Hitachi, Ltd.), a size change during thevacuum holding duration was determined. After an exposure dose whichprovided a 1:1 resolution at the top and bottom of a 0.12 μmline-and-space pattern was determined, a 0.12 μm line-and-space patternat that exposure dose was measured for line width in both the initiallyexposed area and the 20 hour later exposed area. A differencetherebetween is the size change. Positive values of size change indicatethat the resist sensitivity varies toward a higher level during vacuumholding whereas negative values indicate that the sensitivity variestoward a lower level. The results are shown in Table 9.

TABLE 9 Size change Resist protective topcoat (nm) TC-20 0 TC-21 −1TC-22 0 TC-23 0 TC-24 −1 TC-25 −1 TC-26 0 TC-27 0 TC-28 0 no protectivefilm −9

In the EB imagewise exposure test, the application of inventive resistprotective topcoats (TC-20 to 28) improved the stability of resistduring post-exposure vacuum holding.

[Evaluation of Resist Composition]

A resist solution was prepared by dissolving 5 g of Resist Polymer, 0.25g of an additive polymer selected from Polymers 8 to 19 and ComparativePolymer 1, 0.25 g of PAG1, and 0.05 g of Quencher 1 (all shown below) in75 g of PGMEA and filtering through a polypropylene filter having a poresize of 0.2 μm. For comparative purposes, a resist solution wassimilarly prepared without adding the additive polymer.

An antireflective coating ARC-29A (Nissan Chemical Co., Ltd.) wasdeposited on a silicon substrate to a thickness of 87 nm. The resistsolution was applied onto the ARC and baked at 120° C. for 60 seconds toform a resist film of 150 nm thick.

A contact angle with water of the resist film was measured, using aninclination contact angle meter Drop Master 500 by Kyowa InterfaceScience Co., Ltd. Specifically, the wafer covered with the resist filmwas kept horizontal, and 50 μL of pure water was dropped on the resistfilm to form a droplet. While the wafer was gradually inclined, theangle (sliding angle) at which the droplet started sliding down wasdetermined as well as receding contact angle. The results are shown inTable 10.

TABLE 10 Receding Sliding contact Anion 75-nm Additive angle angleleach-out Sensitivity pattern Polymer (°) (°) (ppb) (mJ/cm²) profilePolymer 8 17 74 7 34 rectangular Polymer 9 11 84 6 35 rectangularPolymer 10 9 86 7 33 rectangular Polymer 11 9 87 6 34 rectangularPolymer 12 11 84 6 35 rectangular Polymer 13 8 87 7 32 rectangularPolymer 14 10 83 7 32 rectangular Polymer 15 12 74 6 33 rectangularPolymer 16 12 74 7 33 rectangular Polymer 17 14 73 6 32 rectangularPolymer 18 14 74 6 32 rectangular Polymer 19 13 75 7 33 rectangularComparative 15 69 7 32 rectangular Polymer 1 not added 28 40 60 45 T-top

A smaller sliding angle indicates an easier flow of water on the resistfilm. A larger receding contact angle indicates that fewer liquiddroplets are left during high-speed scan exposure. It is demonstrated inTable 10 that the inclusion of the additive polymer of the invention ina resist solution achieves a drastic improvement in the receding contactangle of photoresist film without adversely affecting the sliding angle,as compared with those photoresist films free of the additive polymer.

Also, the resist film-bearing wafer (prepared above) was irradiatedthrough an open frame at an energy dose of 50 mJ/cm² using an ArFscanner S305B (Nikon Corp.). Then a true circle ring of Teflon® havingan inner diameter of 10 cm was placed on the resist film, 10 mL of purewater was carefully injected inside the ring, and the resist film waskept in contact with water at room temperature for 60 seconds.Thereafter, the water was recovered, and a concentration of photoacidgenerator (PAG1) anion in the water was measured by an LC-MS analyzer(Agilent). The anion concentration measured indicates an amount ofanions leached out for 60 seconds. The results are also shown in Table10. It is evident from Table 10 that a photoresist film formed from aresist solution containing the inventive polymer is effective ininhibiting the PAG from being leached out of the film in water.

Further, the resist film-bearing wafer (prepared above) was exposed bymeans of an ArF scanner model S307E (Nikon Corp., NA 0.85, σ 0.93, 4/5annular illumination, 6% halftone phase shift mask), rinsed for 5minutes while splashing pure water, post-exposure baked (PEB) at 110° C.for 60 seconds, and developed with a 2.38 wt % TMAH aqueous solution for60 seconds, forming a 75-nm line-and-space pattern. The wafer wassectioned, and the profile and sensitivity of the 75-nm line-and-spacepattern were evaluated. The results are also shown in Table 10.

As seen from Table 10, when exposure is followed by water rinsing, theresist film having the additive polymer of the invention formulatedtherein formed a pattern of rectangular profile, in stark contrast withthe resist film free of the additive polymer of the invention forming apattern of T-top profile.

Japanese Patent Application Nos. 2008-279212, 2008-279224 and2008-279231 are incorporated herein by reference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A fluorinated monomer of cyclic acetal structure having the generalformula (1):

wherein R is a straight, branched or cyclic C₁-C₂₀ alkyl group in whichat least one hydrogen atom may be substituted by a halogen atom or atleast one methylene moiety may be substituted by an oxygen atom orcarbonyl group, and Z is a divalent organic group which is attached atopposite ends to the alkylenoxy group to form a 5- or 6-membered ringand which contains a polymerizable unsaturated group.
 2. A fluorinatedmonomer of cyclic acetal structure having the general formula (2), (3)or (4):

wherein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(2a), R^(2b),R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, with the proviso that said ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group, R⁴ is astraight, branched or cyclic C₁-C₂₀ alkyl group in which at least onehydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group,R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, at least one ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) is a monovalentorganic group containing a polymerizable unsaturated group, or any twoof R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond togetherto form a ring with the carbon atom to which they are attached, with theproviso that said ring contains a polymerizable unsaturated group whenthe remaining groups of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) which do not participate in the ring formation do not contain apolymerizable unsaturated group, R^(8a), R^(8b), R^(9a), and R^(9b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, at leastone of R^(8a), R^(8b), R^(9a), and R^(9b) is a monovalent organic groupcontaining a polymerizable unsaturated group, or any two of R^(8a),R^(8b), R^(9a), and R^(9b) may bond together to form a ring with thecarbon atom to which they are attached, with the proviso that said ringcontains a polymerizable unsaturated group when the remaining groups ofR^(8a), R^(8b), R^(9a), and R^(9b) which do not participate in the ringformation do not contain a polymerizable unsaturated group.
 3. Afluorinated monomer of cyclic acetal structure having the generalformula (2-1), (3-1) or (4-1):

wherein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(2a), R^(2b),R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, with the proviso that said ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group, R^(5a),R^(5b), R^(6a), R^(6b) , R^(7a), and R^(7b) are each independently asingle hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, at least one of R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), and R^(7b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(5a), R^(5b), R^(6a),R^(6b), R^(7a), and R^(7b) may bond together to form a ring with thecarbon atom to which they are attached, with the proviso that said ringcontains a polymerizable unsaturated group when the remaining groups ofR^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) which do notparticipate in the ring formation do not contain a polymerizableunsaturated group, R^(8a), R^(8b), R^(9a), and R^(9b) are eachindependently a single bond, hydrogen, hydroxyl, halogen, or a straight,branched or cyclic monovalent C₁-C₁₅ organic group, at least one ofR^(8a), R^(8b), R^(9a), and R^(9b) is a monovalent organic groupcontaining a polymerizable unsaturated group, or any two of R^(8a),R^(8b), R^(9a), and R^(9b) may bond together to form a ring with thecarbon atom to which they are attached, with the proviso that said ringcontains a polymerizable unsaturated group when the remaining groups ofR^(8a), R^(8b), R^(9a), and R^(9b) which do not participate in the ringformation do not contain a polymerizable unsaturated group, and R¹⁰ is astraight, branched or cyclic C₁-C₁₉ alkyl group in which at least onehydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group.4. A fluorinated monomer of cyclic acetal structure having the generalformula (2-2), (3-2) or (4-2):

wherein R^(2a), R^(2b), R^(3a), and R^(3b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(2a), R^(2b),R^(3a), and R^(3b) is a monovalent organic group containing apolymerizable unsaturated group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, with the proviso that said ring contains apolymerizable unsaturated group when the remaining groups of R^(2a),R^(2b), R^(3a), and R^(3b) which do not participate in the ringformation do not contain a polymerizable unsaturated group, R^(5a),R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) are each independently asingle bond, hydrogen, hydroxyl, halogen, or a straight, branched orcyclic monovalent C₁-C₁₅ organic group, at least one of R^(5a), R^(5b),R^(6a), R^(6b), R^(7a), and R^(7b) is a monovalent organic groupcontaining a polymerizable unsaturated group, or any two of R^(5a),R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b) may bond together to form aring with the carbon atom to which they are attached, with the provisothat said ring contains a polymerizable unsaturated group when theremaining groups of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)which do not participate in the ring formation do not contain apolymerizable unsaturated group, R^(8a), R^(8b), R^(9a), and R^(9b) areeach independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, at leastone of R^(8a), R^(8b), R^(9a), and R^(9b) is a monovalent organic groupcontaining a polymerizable unsaturated group, or any two of R^(8a),R^(8b), R^(9a), and R^(9b) may bond together to form a ring with thecarbon atom to which they are attached, with the proviso that said ringcontains a polymerizable unsaturated group when the remaining groups ofR^(8a), R^(8b), R^(9a), and R^(9b) which do not participate in the ringformation do not contain a polymerizable unsaturated group, R¹¹ ishydrogen or a straight, branched or cyclic C₁-C₁₈ alkyl group in whichat least one hydrogen atom may be substituted by a halogen atom or atleast one methylene moiety may be substituted by an oxygen atom orcarbonyl group, and R¹² is a straight, branched or cyclic C₁-C₁₉ alkylgroup in which at least one hydrogen atom may be substituted by ahalogen atom or at least one methylene moiety may be substituted by anoxygen atom or carbonyl group, or R¹¹ and R¹² may bond together to forma cyclic structure with the carbon and oxygen atoms to which they areattached.
 5. The fluorinated monomer of cyclic acetal structure of claim1 wherein the polymerizable unsaturated group is a group of acrylate,methacrylate or α-trifluoromethylacrylate structure having the generalformula (A):

wherein R¹⁵ is hydrogen, methyl or trifluoromethyl, and the broken linedesignates a valence bond.
 6. The fluorinated monomer of cyclic acetalstructure of claim 1 wherein the polymerizable unsaturated group is agroup of unsaturated hydrocarbon structure having the general formula(B) or (C):

wherein p and q are each independently 1 or 0, and the broken linedesignates a valence bond.
 7. A polymer comprising recurring units ofthe general formula (5) and having a weight average molecular weight of1,000 to 500,000,

wherein R¹ is hydrogen, methyl or trifluoromethyl, and X is a structurehaving the general formula (X-1), (X-2) or (X-3), in formula (X-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (X-1) is linked to the —(C═O)—O—linkage in recurring unit (5) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (X-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (X-2) is linked to the —(C═O)—O— linkage inrecurring unit (5) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (X-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), R⁴ is a straight, branched or cyclicC₁-C₂₀ alkyl group in which at least one hydrogen atom may besubstituted by a halogen atom or at least one methylene moiety may besubstituted by an oxygen atom or carbonyl group, with the proviso thatwhen the structure (X-1), (X-2) or (X-3) is linked to the —(C═O)—O—linkage in recurring unit (5) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 8. A polymer comprisingrecurring units of the general formula (6) and having a weight averagemolecular weight of 1,000 to 500,000,

wherein R¹ is hydrogen, methyl or trifluoromethyl, and Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3), in formula (Y-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (Y-1) is linked to the —(C═O)—O—linkage in recurring unit (6) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (Y-2), R^(5a),R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (Y-2) is linked to the —(C═O)—O— linkage inrecurring unit (6) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (Y-3), R^(8a), R^(8b), R^(9a), andR^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen,or a straight, branched or cyclic monovalent C₁-C₁₅ organic group, orany two of R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to forma ring with the carbon atom to which they are attached, the structure(Y-3) is linked to the —(C═O)—O— linkage in recurring unit (6) via anyone of R^(8a), R^(8b), R^(9a), and R^(9b), and R¹⁰ is a straight,branched or cyclic C₁-C₁₉ alkyl group in which at least one hydrogenatom may be substituted by a halogen atom or at least one methylenemoiety may be substituted by an oxygen atom or carbonyl group, with theproviso that when the structure (Y-1), (Y-2) or (Y-3) is linked to the—(C═O)—O— linkage in recurring unit (6) via a linking group which is anyone of R^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b),R^(7a)R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group isan organic group as defined above, but having a valence bond as a resultof one hydrogen atom being eliminated therefrom.
 9. A polymer comprisingrecurring units of the general formula (7) and having a weight averagemolecular weight of 1,000 to 500,000,

wherein R¹ is hydrogen, methyl or trifluoromethyl, and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3), in formula (Z-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (Z-1) is linked to the —(C═O)—O—linkage in recurring unit (7) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (Z-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a) and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (Z-2) is linked to the —(C═O)—O— linkage inrecurring unit (7) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (Z-3) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), R¹¹ is hydrogen or a straight,branched or cyclic C₁-C₁₈ alkyl group in which at least one hydrogenatom may be substituted by a halogen atom or at least one methylenemoiety may be substituted by an oxygen atom or carbonyl group, R¹² is astraight, branched or cyclic C₁-C₁₉ alkyl group in which at least onehydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group,or R¹¹ and R¹² may bond together to form a cyclic structure with thecarbon and oxygen atoms to which they are attached, with the provisothat when the structure (Z-1), (Z-2) or (Z-3) is linked to the —(C═O)—O—linkage in recurring unit (7) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 10. The polymer of claim7, further comprising recurring units of one or more type selected fromthe general formulae (8a) to (8f):

wherein R¹ is hydrogen, methyl or trifluoromethyl, R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached, R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group,R¹⁵ is a straight, branched or cyclic C₁-C₁₅ fluoroalkyl group, and R¹⁶is an acid labile group.
 11. A resist protective coating compositioncomprising a polymer comprising recurring units of the general formula(5):

wherein R¹ is hydrogen, methyl or trifluoromethyl, and X is a structurehaving the general formula (X-1), (X-2) or (X-3), in formula (X-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (X-1) is linked to the —(C═O)—O—linkage in recurring unit (5) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (X-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (X-2) is linked to the —(C═O)—O— linkage inrecurring unit (5) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (X-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), R⁴ is a straight, branched or cyclicC₁-C₂₀ alkyl group in which at least one hydrogen atom may besubstituted by a halogen atom or at least one methylene moiety may besubstituted by an oxygen atom or carbonyl group, with the proviso thatwhen the structure (X-1), (X-2) or (X-3) is linked to the —(C═O)—O—linkage in recurring unit (5) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 12. A resist protectivecoating composition comprising.a polymer comprising recurring units ofthe general formula (6):

wherein R¹ is hydrogen, methyl or trifluoromethyl, and Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3), in formula (Y-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (Y-1) is linked to the —(C═O)—O—linkage in recurring unit (6) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (Y-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (Y-2) is linked to the —(C═O)—O— linkage inrecurring unit (6) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (Y-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (Y-3) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), and R¹⁰ is i a straight, branched orcyclic C₁-C₁₉ alkyl group in which at least one hydrogen atom may besubstituted by a halogen atom or at least one methylene moiety may besubstituted by an oxygen atom or carbonyl group, with the proviso thatwhen the structure (Y-1), (Y-2) or (Y-3) is linked to the —(C═O)—O—linkage in recurring unit (6) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 13. A resist protectivecoating composition comprising a polymer comprising recurring units ofthe general formula (7):

wherein R¹ is hydrogen, methyl or trifluoromethyl, and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3), in formula (Z-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (Z-1) is linked to the —(C═O)—O—linkage in recurring unit (7) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (Z-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (Z-2) is linked to the —(C═O)—O— linkage inrecurring unit (7) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (Z-3) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), R¹¹ is hydrogen or a straight,branched or cyclic C₁-C₁₈ alkyl group in which at least one hydrogenatom may be substituted by a halogen atom or at least one methylenemoiety may be substituted by an oxygen atom or carbonyl group, R¹² is astraight, branched or cyclic C₁-C₁₉ alkyl group in which at least onehydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group,or R¹¹ and R¹² may bond together to form a cyclic structure with thecarbon and oxygen atoms to which they are attached, with the provisothat when the structure (Z-1), (Z-2) or (Z-3) is linked to the —(C═O)—O—linkage in recurring unit (7) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 14. The resist protectivecoating composition of claim 11 wherein said polymer further comprisesrecurring units of one or more type selected from the general formulae(8a) to (8f):

wherein R¹ is hydrogen, methyl or trifluoromethyl, R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached, R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group,R¹⁵ is a straight, branched or cyclic C₁-C₁₅ fluoroalkyl group, and R¹⁶is an acid labile group.
 15. The protective coating composition of claim11, further comprising a second polymer comprising recurring units ofthe general formula (9) or (10):

wherein R^(31a) and R^(31b) are hydrogen or methyl, R³² is a singlebond, C₁-C₄ alkylene, phenylene, —C(═O)—O—, or —C(═O)—NH—, R³³ is asingle bond or a straight, branched or cyclic C₁-C₈ alkylene group,R^(34a) to R^(34d) and R^(36a) to R^(36c) are each independentlyhydrogen, a straight, branched or cyclic C₁-C₁₂ alkyl, alkenyl, oxoalkylor oxoalkenyl group, C₆-C₂₀ aryl group, or C₇-C₁₂ aralkyl oraryloxoalkyl group, in which some or all hydrogen atoms may besubstituted by alkoxy groups, R^(34a) to R^(34d) and R^(36a) to R^(36c)may contain a nitrogen atom, ether group, ester group, hydroxyl group orcarboxyl group therein, any two of R^(34a) to R^(34d) and R^(36a) toR^(36c) may bond together to form a ring with the nitrogen atom to whichthey are attached, and when they form a ring, they are eachindependently a C₃-C₁₅ alkylene or a hetero-aromatic ring having thenitrogen atom therein, R³⁵ is a straight, branched or cyclic C₁-C₈alkylene group, and R³⁷ is a straight, branched or cyclic C₁-C₂₀ alkylgroup which may contain carbonyl, ester, ether or halogen, or a C₆-C₁₅aryl group which may contain carbonyl, ester, ether, halogen, or C₁-C₁₅alkyl or fluoroalkyl.
 16. The protective coating composition of claim15, wherein the second polymer further comprises recurring units of thegeneral formula (11):

wherein R^(31c) is hydrogen or methyl, R^(38a) and R^(38b) are hydrogenor a straight, branched or cyclic C₁-C₁₅ alkyl group, or R^(38a) andR^(38b) may bond together to form a ring with the carbon atom to whichthey are attached.
 17. The protective coating composition of claim 11,further comprising a solvent.
 18. The protective coating composition ofclaim 17 wherein the solvent comprises an ether compound of 8 to 12carbon atoms.
 19. The protective coating composition of claim 17 whereinthe solvent comprises at least one ether compound of 8 to 12 carbonatoms selected from the group consisting of di-n-butyl ether, diisobutylether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether,di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether.
 20. Theprotective coating composition of claim 18 wherein the solvent comprisesa mixture of the ether compound and 0.1 to 90% by weight of an alcoholof 4 to 10 carbon atoms.
 21. A pattern forming process comprising thesteps of (1) applying a resist material onto a substrate to form aphotoresist film, (2) applying the resist protective coating compositionof claim 11 onto the photoresist film to form a protective coatingthereon, (3) heat treating and exposing the coated substrate tohigh-energy radiation from a projection lens through a photomask whileholding a liquid between the substrate and the projection lens, and (4)developing with a developer.
 22. The process of claim 21 wherein theliquid is water.
 23. The process of claim 21 wherein the high-energyradiation has a wavelength in the range of 180 to 250 nm.
 24. Theprocess of claim 21 wherein the developing step uses a liquid alkalinedeveloper for thereby developing the photoresist film to form a resistpattern and stripping the resist protective coating therefrom at thesame time.
 25. A lithography process for forming a pattern, comprisingthe steps of forming a protective coating on a photoresist layerdisposed on a mask blank, exposing the layer structure in vacuum toelectron beam, and developing, the protective coating being formed ofthe protective coating composition of claim
 11. 26. A resist compositioncomprising (A) a polymer comprising recurring units of the generalformula (5), (B) a base polymer having a structure derived from lactonering, hydroxyl group and/or maleic anhydride, said base polymer becomingsoluble in alkaline developer under the action of acid, (C) a compoundcapable of generating an acid upon exposure to high-energy radiation,and (D) an organic solvent,

wherein R¹ is hydrogen, methyl or trifluoromethyl, and X is a structurehaving the general formula (X-1), (X-2) or (X-3), in formula (X-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (X-1) is linked to the —(C═O)—O—linkage in recurring unit (5) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (X-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (X-2) is linked to the —(C═O)—O— linkage inrecurring unit (5) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (X-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (X-3) islinked to the —(C═O)—O— linkage in recurring unit (5) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), R⁴ is a straight, branched or cyclicC₁-C₂₀ alkyl group in which at least one hydrogen atom may besubstituted by a halogen atom or at least one methylene moiety may besubstituted by an oxygen atom or carbonyl group, with the proviso thatwhen the structure (X-1), (X-2) or (X-3) is linked to the —(C═O)—O—linkage in recurring unit (5) via a linking group which is any one ofR^(2a)R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 27. A resist compositioncomprising (A) a polymer comprising recurring units of the generalformula (6), (B) a base polymer having a structure derived from lactonering, hydroxyl group and/or maleic anhydride, said base polymer becomingsoluble in alkaline developer under the action of acid, (C) a compoundcapable of generating an acid upon exposure to high-energy radiation,and (D) an organic solvent.

wherein R¹ is hydrogen, methyl or trifluoromethyl, and Y is a structurehaving the general formula (Y-1), (Y-2) or (Y-3), in formula (Y-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (Y-1) is linked to the —(C═O)—O—linkage in recurring unit (6) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (Y-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (Y-2) is linked to the —(C═O)—O— linkage inrecurring unit (6) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (Y-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (Y-3) islinked to the —(C═O)—O— linkage in recurring unit (6) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), and R¹⁰ is a straight, branched orcyclic C₁-C₁₉ alkyl group in which at least one hydrogen atom may besubstituted by a halogen atom or at least one methylene moiety may besubstituted by an oxygen atom or carbonyl group, with the proviso thatwhen the structure (Y-1), (Y-2) or (Y-3) is linked to the —(C═O)—O—linkage in recurring unit (6) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 28. A resist compositioncomprising (A) a polymer comprising recurring units of the generalformula (7), (B) a base polymer having a structure derived from lactonering, hydroxyl group and/or maleic anhydride, said base polymer becomingsoluble in alkaline developer under the action of acid, (C) a compoundcapable of generating an acid upon exposure to high-energy radiation,and (D) an organic solvent,

wherein R¹ is hydrogen, methyl or trifluoromethyl, and Z is a structurehaving the general formula (Z-1), (Z-2) or (Z-3), in formula (Z-1),R^(2a), R^(2b), R^(3a), and R^(3b) are each independently a single bond,hydrogen, hydroxyl, halogen, or a straight, branched or cyclicmonovalent C₁-C₁₅ organic group, or any two of R^(2a), R^(2b), R^(3a),and R^(3b) may bond together to form a ring with the carbon atom towhich they are attached, the structure (Z-1) is linked to the —(C═O)—O—linkage in recurring unit (7) via any one of R^(2a), R^(2b), R^(3a), andR^(3b), in formula (Z-2), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), andR^(7b) are each independently a single bond, hydrogen, hydroxyl,halogen, or a straight, branched or cyclic monovalent C₁-C₁₅ organicgroup, or any two of R^(5a), R^(5b), R^(6a), R^(6b), R^(7a), and R^(7b)may bond together to form a ring with the carbon atom to which they areattached, the structure (Z-2) is linked to the —(C═O)—O— linkage inrecurring unit (7) via any one of R^(5a), R^(5b), R^(6a), R^(6b),R^(7a), and R^(7b), in formula (Z-3), R^(8a), R^(8b), R^(9a), and R^(9b)are each independently a single bond, hydrogen, hydroxyl, halogen, or astraight, branched or cyclic monovalent C₁-C₁₅ organic group, or any twoof R^(8a), R^(8b), R^(9a), and R^(9b) may bond together to form a ringwith the carbon atom to which they are attached, the structure (Z-3) islinked to the —(C═O)—O— linkage in recurring unit (7) via any one ofR^(8a), R^(8b), R^(9a), and R^(9b), R¹¹ is hydrogen or a straight,branched or cyclic C₁-C₁₈ alkyl group in which at least one hydrogenatom may be substituted by a halogen atom or at least one methylenemoiety may be substituted by an oxygen atom or carbonyl group, R¹² is astraight, branched or cyclic C₁-C₁₉ alkyl group in which at least onehydrogen atom may be substituted by a halogen atom or at least onemethylene moiety may be substituted by an oxygen atom or carbonyl group,or R¹¹ and R¹² may bond together to form a cyclic structure with thecarbon and oxygen atoms to which they are attached, with the provisothat when the structure (Z-1), (Z-2) or (Z-3) is linked to the —(C═O)—O—linkage in recurring unit (7) via a linking group which is any one ofR^(2a), R^(2b), R^(3a), R^(3b), R^(5a), R^(5b), R^(6a), R^(6b), R^(7a),R^(7b), R^(8a), R^(8b), R^(9a), and R^(9b), the linking group is anorganic group as defined above, but having a valence bond as a result ofone hydrogen atom being eliminated therefrom.
 29. A resist compositioncomprising (A) a polymer, (B) a base polymer having a structure derivedfrom lactone ring, hydroxyl group and/or maleic anhydride, said basepolymer becoming soluble in alkaline developer under the action of acid,(C) a compound capable of generating an acid upon exposure tohigh-energy radiation, and (D) an organic solvent, said polymer (A)comprises recurring units as set forth in claim 26, and furtherrecurring units of one or more type selected from the general formulae(8a) to (8f):

wherein R¹ is hydrogen, methyl or trifluoromethyl, R^(13a) and R^(13b)each are hydrogen or a straight, branched or cyclic C₁-C₁₅ alkyl group,or R^(13a) and R^(13b) may bond together to form a ring with the carbonatom to which they are attached, R¹⁴ is hydrogen, a straight, branchedor cyclic C₁-C₁₅ alkyl or fluoroalkyl group, or an acid labile group,R¹⁵ is a straight, branched or cyclic C₁-C₁₅ fluoroalkyl group, and R¹⁶is an acid labile group.
 30. The resist composition of claim 26, furthercomprising (E) a basic compound.
 31. The resist composition of claim 26,further comprising (F) a dissolution regulator.
 32. A pattern formingprocess comprising the steps of: (1) applying the resist composition ofclaim 26 onto a substrate to form a resist film, (2) heat treating theresist film and exposing it to high-energy radiation through aphotomask, and (3) developing the exposed resist film with a developer.33. A pattern forming process comprising the steps of: (1) applying theresist composition of claim 26 onto a substrate to form a resist film,(2) heat treating the coated substrate, and exposing it to high-energyradiation through a photomask while keeping a liquid between aprojection lens and the coated substrate, and (3) developing the exposedresist film with a developer.
 34. A pattern forming process comprisingthe steps of: (1) applying the resist composition of claim 26 onto asubstrate to form a resist film, (2) forming a protective coating on theresist film, (3) heat treating the coated substrate, and exposing it tohigh-energy radiation through a photomask while keeping a liquid betweena projection lens and the coated substrate, and (4) developing theexposed resist film with a developer.
 35. The process of claim 33,wherein the liquid is water.
 36. The process of claim 32, wherein anexposure light source emits high-energy radiation having a wavelength of180 to 250 nm.
 37. A pattern forming process comprising the steps of:(1) applying the resist composition of claim 26 onto a mask blanksubstrate to form a coating, (2) heat treating the coating andirradiating it in vacuum with an electron beam, and (3) developing thecoating with a developer.